Re: [zfs-discuss] repost - high read iops
On Mon, Dec 28, 2009 at 01:40:03PM -0800, Brad wrote: This doesn't make sense to me. You've got 32 GB, why not use it? Artificially limiting the memory use to 20 GB seems like a waste of good money. I'm having a hard time convincing the dbas to increase the size of the SGA to 20GB because their philosophy is, no matter what eventually you'll have to hit disk to pick up data thats not stored in cache (arc or l2arc). The typical database server in our environment holds over 3TB of data. Brad, are your DBAs aware that if you increase your SGA (currently 4 GB) - to 8 GB - you get 100 % more memory for SGA - to 16 GB - you get 300 % more memory for SGA - to 20 GB - you get 400 % ... If they are not aware, well ... But try to be patient - I had similar situation. It took quite long time to convince our DBA to increase SGA from 16 GB to 20 GB. Finally they did :-) You can always use stronger argument that not using already bought memory is wasting of _money_. Regards Przemyslaw Bak (przemol) -- http://przemol.blogspot.com/ -- Sprawdz, co przyniesie Nowy Rok! Zapytaj wrozke http://link.interia.pl/f254d ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] new logbias property
On Tue, Aug 11, 2009 at 05:42:31AM -0700, Robert Milkowski wrote:
Hi,
I like the new feature but I was thinking that maybe the keywords being used
should be different?
Currently it is:
# zfs set logbias=latency {dataset}
# zfs set logbias=throughput {dataset}
Maybe it would be more clear this way:
# zfs set logdest=dedicated {dataset}
# zfs set logdest=pool {dataset}
or even intentlog={dedicated|pool} ?
IMHO it would better describe what the feature actually does.
I am not sure if 'logbias' is better then 'logdest' but IMHO
'latency' and 'throughput' is much more intuitive :-)
Regards
Przemyslaw Bak (przemol)
--
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Re: [zfs-discuss] zfs compression - btrfs compression
On Mon, Nov 03, 2008 at 12:33:52PM -0600, Bob Friesenhahn wrote: On Mon, 3 Nov 2008, Robert Milkowski wrote: Now, the good filter could be to use MAGIC numbers within files or approach btrfs come up with, or maybe even both combined. You are suggesting that ZFS should detect a GIF or JPEG image stored in a database BLOB. That is pretty fancy functionality. ;-) Maybe some general approach (not strictly GIF- or JPEG-oriented) could be useful. Give people a choice and they will love ZFS even more. Regards Przemyslaw Bak (przemol) -- http://przemol.blogspot.com/ -- Konkurs! Wygraj telewizor LCD! Sprawdz http://link.interia.pl/f1f61 ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Automatic removal of old snapshots
On Thu, Sep 25, 2008 at 11:43:51AM +0200, Nils Goroll wrote: Before re-inventing the wheel, does anyone have any nice shell script to do this kind of thing (to be executed from cron)? http://blogs.sun.com/timf/entry/zfs_automatic_snapshots_0_10 http://blogs.sun.com/timf/entry/zfs_automatic_snapshots_0_11 Storage Checkpoints in Veritas software has this feature (removing the oldest checkpoint in case of 100% filesystem usage) by default. Why not add such option to ZFS ? Regards Przemyslaw Bak (przemol) -- http://przemol.blogspot.com/ -- Znajdź mieszkanie w Twoim regionie! kliknij http://link.interia.pl/f1f19 ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Automatic removal of old snapshots
On Thu, Sep 25, 2008 at 11:30:04AM +0100, Tim Foster wrote: On Thu, 2008-09-25 at 12:07 +0200, [EMAIL PROTECTED] wrote: On Thu, Sep 25, 2008 at 11:43:51AM +0200, Nils Goroll wrote: Storage Checkpoints in Veritas software has this feature (removing the oldest checkpoint in case of 100% filesystem usage) by default. Why not add such option to ZFS ? - because we shouldn't assume a user's intentions - some would consider automatic destruction of data (even historical data) a p1 bug. Tim, nobody is going to assume user's intentions. Just give us snapshot-related property which we can set to on/off and everybody can setup zfs according to his/her needs. Regards Przemyslaw Bak (przemol) -- http://przemol.blogspot.com/ -- Znajdź mieszkanie w Twoim regionie! kliknij http://link.interia.pl/f1f19 ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] filebench for Solaris 10?
On Sat, Feb 16, 2008 at 07:26:27PM -0600, Bob Friesenhahn wrote: Some of us are still using Solaris 10 since it is the version of Solaris released and supported by Sun. The 'filebench' software from SourceForge does not seem to install or work on Solaris 10. [...] I am not sure if you are right: bash-3.00# cat /etc/release Solaris 10 8/07 s10x_u4wos_12b X86 Copyright 2007 Sun Microsystems, Inc. All Rights Reserved. Use is subject to license terms. Assembled 16 August 2007 bash-3.00# pkginfo|grep -i filebench application filebenchFileBench bash-3.00# pkginfo -l filebench PKGINST: filebench NAME: FileBench CATEGORY: application ARCH: i386 VERSION: 1.1.0 BASEDIR: /opt VENDOR: filebench.org DESC: FileBench PSTAMP: 1.1.0_snv INSTDATE: Jan 28 2008 13:20 EMAIL: [EMAIL PROTECTED] STATUS: completely installed FILES: 261 installed pathnames 5 linked files 27 directories 62 executables 1 setuid/setgid executables 20158 blocks used (approx) Regards przemol -- http://przemol.blogspot.com/ -- Myslisz, ze nie ma sniegu? Sprawdź gdzie mozesz poszusowac na nartach http://link.interia.pl/f1cfb ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] vxfs vs ufs vs zfs
Hello, I have just done comparison of all the above filesystems using the latest filebench. If you are interested: http://przemol.blogspot.com/2008/02/zfs-vs-vxfs-vs-ufs-on-x4500-thumper.html Regards przemol -- http://przemol.blogspot.com/ -- Myslisz, ze nie ma sniegu? Sprawdź gdzie mozesz poszusowac na nartach http://link.interia.pl/f1cfb ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Which DTrace provider to use
On Tue, Feb 12, 2008 at 10:21:44PM -0800, Jonathan Loran wrote: Hi List, I'm wondering if one of you expert DTrace guru's can help me. I want to write a DTrace script to print out a a histogram of how long IO requests sit in the service queue. I can output the results with the quantize method. I'm not sure which provider I should be using for this. Does anyone know? I can easily adapt one of the DTrace Toolkit routines for this, if I can find the provider. I'll also throw out the problem I'm trying to meter. We are using ZFS on a large SAN array (4TB). The pool on this array serves up a lot of users, (250 home file systems/directories) and also /usr/local and other OTS software. It works fine most of the time, but then gets overloaded during busy periods. I'm going to reconfigure the array to help with this, but I sure would love to have some metrics to know how big a difference my tweaks are making. Basically, the problem users experience, when the load shoots up are huge latencies. An ls on a non-cached directory, which usually is instantaneous, will take 20, 30, 40 seconds or more. Then when the storage array catches up, things get better. My clients are not happy campers. I know, I know, I should have gone with a JBOD setup, but it's too late for that in this iteration of this server. We we set this up, I had the gear already, and it's not in my budget to get new stuff right now. Thanks for any help anyone can offer. I have faced similar problem (although not exactly the same) and was going to monitor disk queue with dtrace but couldn't find any docs/urls about it. Finally asked Chris Gerhard for help. He partially answered via his blog: http://blogs.sun.com/chrisg/entry/latency_bubble_in_your_io Maybe it helps you. Regards przemol -- http://przemol.blogspot.com/ -- Masz ostatnia szanse ! Sprawdz http://link.interia.pl/f1d02 ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Ditto blocks in S10U4 ?
bash-3.00# cat /etc/release Solaris 10 8/07 s10x_u4wos_12b X86 Copyright 2007 Sun Microsystems, Inc. All Rights Reserved. Use is subject to license terms. Assembled 16 August 2007 (with all the latest patches) bash-3.00# zpool list NAMESIZEUSED AVAILCAP HEALTH ALTROOT zpool1 20.8T 5.44G 20.8T 0% ONLINE - bash-3.00# zpool upgrade -v This system is currently running ZFS version 4. The following versions are supported: VER DESCRIPTION --- 1 Initial ZFS version 2 Ditto blocks (replicated metadata) 3 Hot spares and double parity RAID-Z 4 zpool history For more information on a particular version, including supported releases, see: http://www.opensolaris.org/os/community/zfs/version/N Where 'N' is the version number. bash-3.00# zfs set copies=2 zpool1 cannot set property for 'zpool1': invalid property 'copies' From http://www.opensolaris.org/os/community/zfs/version/2/ ... This version includes support for Ditto Blocks, or replicated metadata. Can anybody shed any light on it ? Regards przemol -- http://przemol.blogspot.com/ -- Kogo Doda ciagnela do lozka? Sprawdz http://link.interia.pl/f1cde ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] ZFS write time performance question
On Wed, Dec 05, 2007 at 09:02:43PM -0800, Tim Cook wrote: what firmware revision are you at? Revision: 415G Regards przemol -- http://przemol.blogspot.com/ -- A co by bylo, gdybys to TY rzadzil? Kliknij http://link.interia.pl/f1c91 ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] ZFS write time performance question
On Thu, Nov 29, 2007 at 02:05:13PM -0800, Brendan Gregg - Sun Microsystems wrote: I'd recommend running filebench for filesystem benchmarks, and see what the results are: http://www.solarisinternals.com/wiki/index.php/FileBench Filebench is able to purge the ZFS cache (export/import) between runs, and can be customised to match real world workloads. It should improve the accuracy of the numbers. I'm expecting filebench to become *the* standard tool for filesystem benchmarks. And some results (for OLTP workload): http://przemol.blogspot.com/2007/08/zfs-vs-vxfs-vs-ufs-on-scsi-array.html Regards przemol -- http://przemol.blogspot.com/ -- A co by bylo, gdybys to TY rzadzil? Kliknij http://link.interia.pl/f1c91 ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Direct I/O ability with zfs?
On Tue, Oct 02, 2007 at 01:20:24PM -0600, eric kustarz wrote: On Oct 2, 2007, at 1:11 PM, David Runyon wrote: We are using MySQL, and love the idea of using zfs for this. We are used to using Direct I/O to bypass file system caching (let the DB do this). Does this exist for zfs? Not yet, see: 6429855 Need way to tell ZFS that caching is a lost cause Is there a specific reason why you need to do the caching at the DB level instead of the file system? I'm really curious as i've got conflicting data on why people do this. If i get more data on real reasons on why we shouldn't cache at the file system, then this could get bumped up in my priority queue. At least two reasons: http://developers.sun.com/solaris/articles/mysql_perf_tune.html#6 http://blogs.sun.com/glennf/entry/where_do_you_cache_oracle (the first example proofs that this issue is not only Oracle-related) Regards przemol -- http://przemol.blogspot.com/ -- Fajne i smieszne. Zobacz najlepsze filmiki! http://link.interia.pl/f1bbb ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Performance Tuning - ZFS, Oracle and T2000
On Sun, Aug 19, 2007 at 09:32:02AM +0200, Louwtjie Burger wrote: http://blogs.sun.com/realneel/entry/zfs_and_databases http://www.sun.com/servers/coolthreads/tnb/parameters.jsp http://www.sun.com/servers/coolthreads/tnb/applications_oracle.jsp Be careful with long running single queries... you want to throw lots of users at it ... or parallelize as much as possible! Also keep in mind that a T2000 running flat out has the potential to generate LOTS of I/O... it's vital to have a decent storage system supporting it. On 8/19/07, Damian Reed - Systems Support Engineer [EMAIL PROTECTED] wrote: Hi All, We are currently in the process of testing Solaris 10 with ZFS and Oracle and are running it on a T2000. When checking performance statistics on the T2000, we notice that only one thread of the CPU appears to be doing any of the processing. Leaving all other threads seemingly idle. Are there any tuning parameters that need to be set or changed when running Oracle on T2000 using ZFS? Can anyone suggest what I might look for? Any initial suggestions would be greatly appreciated. Regards, Damian Reed The following page might also be helpful: http://blogs.sun.com/ValdisFilks/entry/improving_i_o_throughput_for Regards przemol -- http://przemol.blogspot.com/ -- Jestes kierowca? To poczytaj! http://link.interia.pl/f199e ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] ZFS and VXVM/VXFS
On Mon, Jul 02, 2007 at 12:30:32PM -0700, Richard Elling wrote: Magesh R wrote: We are looking at the alternatives to VXVM/VXFS. One of the feature which we liked in Veritas, apart from the obvious ones is the ability to call the disks by name and group them in to a disk group. Especially in SAN based environment where the disks may be shared by multiple machines, it is very easy to manage them by disk group names rather than cxtxdx numbers. Does zfs offer such capabilities? ZFS greatly simplifies disk management. I would argue that is eliminates the need for vanity naming or some features of diskgroups. I suggest you read through the docs on how to administer and setup ZFS, try a few examples, and then ask specific questions. Nit: You confused me with disks may be shared by multiple machines because LUNs have no protection below the LUN level, and if your disk is a LUN, then sharing it leaves the data unprotected. Perhaps you are speaking of LUNs on a RAID array? -- richard Richard, It is rather rare that in SAN based environment you are given access to particular disks. :-) Magesh, in ZFS world you create pools. Each pool has its own name. Then, later, you refer to each pool (and filesystem) using its name. Regards przemol -- http://przemol.blogspot.com/ -- O Twoich stronach juz się mówi... Na http://link.interia.pl/f1ad3 ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Layout for multiple large streaming writes.
On Mon, Mar 12, 2007 at 09:34:22AM +0100, Robert Milkowski wrote: Hello przemolicc, Monday, March 12, 2007, 8:50:57 AM, you wrote: ppf On Sat, Mar 10, 2007 at 12:08:22AM +0100, Robert Milkowski wrote: Hello Carisdad, Friday, March 9, 2007, 7:05:02 PM, you wrote: C I have a setup with a T2000 SAN attached to 90 500GB SATA drives C presented as individual luns to the host. We will be sending mostly C large streaming writes to the filesystems over the network (~2GB/file) C in 5/6 streams per filesystem. Data protection is pretty important, but C we need to have at most 25% overhead for redundancy. C Some options I'm considering are: C 10 x 7+2 RAIDZ2 w/ no hotspares C 7 x 10+2 RAIDZ2 w/ 6 spares C Does any one have advice relating to the performance or reliability to C either of these? We typically would swap out a bad drive in 4-6 hrs and C we expect the drives to be fairly full most of the time ~70-75% fs C utilization. On x4500 with a config: 4x 9+2 RAID-z2 I get ~600MB/s logical (~700-800 with redundancy overhead). It's somewhat jumpy but it's a known bug in zfs... So in your config, assuming host/SAN/array is not a bottleneck, you should be able to write at least two times more throughput. ppf Look also at: ppf http://sunsolve.sun.com/search/document.do?assetkey=1-9-88385-1 ppf where you have a way to increase the I/O and application performance on ppf T2000. I was talking about x4500 not T2000. But Carisdad mentioned T2000. Regards przemol -- Jestes kierowca? To poczytaj! http://link.interia.pl/f199e ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Re: Re: How much do we really want zpool remove?
On Thu, Feb 22, 2007 at 12:21:50PM -0700, Jason J. W. Williams wrote: Hi Przemol, I think Casper had a good point bringing up the data integrity features when using ZFS for RAID. Big companies do a lot of things just because that's the certified way that end up biting them in the rear. Trusting your SAN arrays is one of them. That all being said, the need to do migrations is a very valid concern. Jason, I don't claim that SAN/RAID solutions are the best and don't have any mistakes/failures/problems. But if SAN/RAID is so bad why companies using them survive ? Imagine also that some company is using SAN/RAID for a few years and doesn't have any problems (or once a few months). Also from time to time they need to migrate between arrays (for whatever reason). Now you come and say that they have unreliable SAN/RAID and you offer something new (ZFS) which is going to make it much more reliable but migration to another array will be painfull. What do you think what they choose ? BTW: I am a fan of ZFS. :-) przemol -- Ustawiaj rekordy DNS dla swojej domeny http://link.interia.pl/f1a1a ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Re: Re: How much do we really want zpool remove?
On Tue, Feb 27, 2007 at 08:29:04PM +1100, Shawn Walker wrote: On 27/02/07, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: On Thu, Feb 22, 2007 at 12:21:50PM -0700, Jason J. W. Williams wrote: Hi Przemol, I think Casper had a good point bringing up the data integrity features when using ZFS for RAID. Big companies do a lot of things just because that's the certified way that end up biting them in the rear. Trusting your SAN arrays is one of them. That all being said, the need to do migrations is a very valid concern. Jason, I don't claim that SAN/RAID solutions are the best and don't have any mistakes/failures/problems. But if SAN/RAID is so bad why companies using them survive ? I think he was trying to say that people that believe that those solutions are reliable just because they are based on SAN/RAID technology and are not aware of the true situation surrounding them. Is the true situation really so bad ? My feeling was that he was trying to say that there is no SAN/RAID solution without data integrity problem. Is it really true ? Does anybody have any paper (*) about percentage of problems in SAN/RAID because of data integrity ? Is it 5 % ? Or 30 % ? Or maybe 60 % ? (*) Maybe such paper/report should be a start point for our discussion. przemol -- Gdy nie ma dzieci... - zobacz http://link.interia.pl/f19eb ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Re: Re: How much do we really want zpool remove?
On Wed, Feb 21, 2007 at 04:43:34PM +0100, [EMAIL PROTECTED] wrote: I cannot let you say that. Here in my company we are very interested in ZFS, but we do not care about the RAID/mirror features, because we already have a SAN with RAID-5 disks, and dual fabric connection to the hosts. But you understand that these underlying RAID mechanism give absolutely no guarantee about data integrity but only that some data was found were some (possibly other) data was written? (RAID5 never verifies the checkum is correct on reads; it only uses it to reconstruct data when reads fail) But you understand that he perhaps knows that but so far nothing wrong happened [*] and migration is still very important feature for him ? [*] almost every big company has its data center with SAN and FC connections with RAID-5 or RAID-10 in their storage arrays and they are treated as reliable przemol -- Wpadka w kosciele - zobacz http://link.interia.pl/f19ea ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] How much do we really want zpool remove?
On Thu, Jan 18, 2007 at 06:55:39PM +0800, Jeremy Teo wrote: On the issue of the ability to remove a device from a zpool, how useful/pressing is this feature? Or is this more along the line of nice to have? If you think remove a device from a zpool = to shrink a pool then it is really usefull. Definitely really usefull. Do you need any example ? przemol -- Lufa dla generala. Zobacz http://link.interia.pl/f19e1 ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Difference between ZFS and UFS with one LUN from a SAN
On Thu, Dec 21, 2006 at 04:45:34PM +0100, Robert Milkowski wrote: Hello Shawn, Thursday, December 21, 2006, 4:28:39 PM, you wrote: SJ All, SJ I understand that ZFS gives you more error correction when using SJ two LUNS from a SAN. But, does it provide you with less features SJ than UFS does on one LUN from a SAN (i.e is it less stable). With only one LUN you still get error detection which UFS doesn't give you. You still can use snapshots, clones, quotas, etc. so in general you still have more features than UFS. Now when in comes to stability - depends. UFS is for years in use while ZFS much younger. More and more people are using ZFS in production and while there're some corner cases mostly performance related, it works really good. And I haven't heard of verified data lost due to ZFS. I've been using ZFS for quite some time (much sooner than it was available in SX) and I haven't also lost any data. Robert, I don't understand why not loosing any data is an advantage of ZFS. No filesystem should lose any data. It is like saying that an advantage of football player is that he/she plays football (he/she should do that !) or an advantage of chef is that he/she cooks (he/she should do that !). Every filesystem should _save_ our data, not lose it. Regards przemol -- Jestes kierowca? To poczytaj! http://link.interia.pl/f199e ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Re: !
Ulrich, in his e-mail Robert mentioned _two_ things regarding ZFS: [1] ability to detect errors (checksums) [2] using ZFS didn't caused data lost so far I completely agree that [1] is wonderful and this is huge advantage. And you also underlined [1] in you e-mail ! The _only_ thing I mentioned is [2]. And I guess Robert wrote about it only because ZFS is relatively young. When you talk about VxFS/UFS you don't underline that they don't lose data - it would be ridiculous. Regards przemol On Fri, Dec 22, 2006 at 11:39:44AM +0100, Ulrich Graef wrote: [EMAIL PROTECTED] wrote: Robert, I don't understand why not loosing any data is an advantage of ZFS. No filesystem should lose any data. It is like saying that an advantage of football player is that he/she plays football (he/she should do that !) or an advantage of chef is that he/she cooks (he/she should do that !). Every filesystem should _save_ our data, not lose it. yes, you are right: every filesystem should save the data. (... and every program should have no error! ;-) Unfortunately there are some cases, where the disks lose data, these cannot be detected by traditional filesystems but with ZFS: * bit rot: some bits on the disk gets flipped (~ 1 in 10^11) (cosmic rays, static particles in airflow, random thermodynamics) * phantom writes: a disk 'forgets' to write data (~ 1 in 10^8) (positioning errors, disk firmware errors, ...) * misdirected reads/writes: disk writes to the wrong position (~ 1 in 10^8) (disks use very small structures, head can move after positioning) * errors on the data transfer connection You can look up the probabilities at several disk vendors, the are published. Traditional filesystems do not check the data they read. You get strange effects when the filesystem code runs with wrong metadata (worst case: panic). If you use the wrong data in your applicaton, you 'only' have the wrong results... ZFS on the contrary checks every block it reads and is able to find the mirror or reconstruct the data in a raidz config. Therefore ZFS uses only valid data and is able to repair the data blocks automatically. This is not possible in a traditional filesystem/volume manager configuration. You may say, you never heard of a disk losing data; but you have heard of systems, which behave strange and a re-installation fixed everything. Or some data have gone bad and you have to recover from backup. It may be, that this was one of these cases. Our service encounters a number of these cases every year, where the customer was not able to re-install or did not want to restore his data, which can be traced back to such a disk error. These are always nasty problems and it gets nastier, because customers have more and more data and there is a trend to save money on backup/restore infrastructures which make it hurt to restore data. Regards, Ulrich -- | Ulrich Graef, Senior Consultant, OS Ambassador \ | Operating Systems, Performance \ Platform Technology \ | Mail: [EMAIL PROTECTED] \ Global Systems Enginering \ |Phone: +49 6103 752 359\ Sun Microsystems Inc \ -- Jestes kierowca? To poczytaj! http://link.interia.pl/f199e ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] A versioning FS
On Fri, Oct 06, 2006 at 11:57:36AM -0700, Matthew Ahrens wrote: [EMAIL PROTECTED] wrote: On Fri, Oct 06, 2006 at 01:14:23AM -0600, Chad Leigh -- Shire.Net LLC wrote: But I would dearly like to have a versioning capability. Me too. Example (real life scenario): there is a samba server for about 200 concurrent connected users. They keep mainly doc/xls files on the server. From time to time they (somehow) currupt their files (they share the files so it is possible) so they are recovered from backup. Having versioning they could be said that if their main file is corrupted they can open previous version and keep working. ZFS snapshots is not solution in this case because we would have to create snapshots for 400 filesystems (yes, each user has its filesystem and I said that there are 200 concurrent connections but there much more accounts on the server) each hour or so. I completely disagree. In this scenario (and almost all others), use of regular snapshots will solve the problem. 'zfs snapshot -r' is extremely fast, and I'm working on some new features that will make using snapshots for this even easier and better-performing. If you disagree, please tell us *why* you think snapshots don't solve the problem. Matt, think of night when some (maybe 5 %) people still work. Having snapshot I would still have to create snapshots for 400 filesystems each hour because I don't know which of them are working. And what about weekend ? Still 400 snaphosts each hour ? And 'zfs list' will list me 400*24*2=19200 lines ? And how about organizations which has thousends people and keep their files on one server ? Or ISP/free e-maila account providers who have millions ? Imagine just ordinary people who use ZFS in their homes and forgot creating snapshots ? Or they turn their computer on once and then don't turn it off: they work daily (and create snapshot an hour) and don't turn it off in the evening but leave it working and downloading some films and musics. Still one snapshot an hour ? How many snapshot's a day, a week a month ? Thousands ? And having ZFS which is _so_easy_ to use does managing so many snapshots is ZFS-like feature ? (ZFS-like = extremely easy). The way ZFS is working right now is that it cares about disks (checksumming), redundancy (raid*) and performance. Having versioning would let ZFS care about people mistakes. And people do mistakes. Yes, Matt, you are right that snapshots are a feature which might be used here but it is not the most convenient in such scenarios. Snapshots are probably much more useful then versioning in predictable scenarios: backup at night, software development (commit new version) etc. In highly unpredictable environment (many users working in _diferent_ hours in different part ot the world) you would have to create many thousands of snapshots. To deal with them might be painfull. Matt, I agree with you that having snapshots *solve* the problem with 400 filesystems because in SVM/UFS environemnt I _wouldn't_ have such solution. But I feel that versioning would be much more convenient here. Imagine that you are the admin of the server and ZFS has versioning: having a choice what would you choose in this case ? przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] A versioning FS
On Fri, Oct 06, 2006 at 02:08:34PM -0700, Erik Trimble wrote: Also, save-early-save-often results in a version explosion, as does auto-save in the app. While this may indeed mean that you have all of your changes around, figuring out which version has them can be massively time-consuming. Let's say you have auto-save set for 5 minutes (very common in MS Word). That gives you 12 versions per hour. If you suddenly decide you want to back up a couple of hours, that leaves you with looking at a whole bunch of files, trying to figure out which one you want. E.g. I want a file from about 3 hours ago. Do I want the one from 2:45, 2:50, 2:55, 3:00, 3:05, 3:10, or 3:15 hours ago? And, what if I've mis-remembered, and it really was closer to 4 hours ago? Yes, the data is eventually there. However, wouldn't a 1-hour snapshot capability have saved you an enormous amount of time, by being able to simplify your search (and, yes, you won't have _exactly_ the version you want, but odds are you will have something close, and you can put all the time you would have spent searching the FV tree into restarting work from the snapshot-ed version). Erik, versioning could be managed by sort of versioning policy managed by users. E.g. if a file, which is going to be saved right now (auto-saving), has a previous version saved within last 30 minuts, don't create another previous version. 10:00 open file f.xls 10:10 (...working...) 10:20 file.xls;1 (...auto save ...) 10:30 (...working...) 10:40 (...auto save ...) -don't create another version because within last 30 minuts there is another, previous version Another policy might be based on number of previous version: e.g. if there are more then 10, purge the older. [...] To me, FV is/was very useful in TOPS-20 and VMS, where you were looking at a system DESIGNED with the idea in mind, already have a user base trained to use and expect it, and virtually all usage was local (i.e. no network filesharing). None of this is true in the UNIX/POSIX world. Versioning could be turned off per filesystem. And also could be inherited from a parent - exactly like current compression. przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] A versioning FS
On Fri, Oct 06, 2006 at 01:14:23AM -0600, Chad Leigh -- Shire.Net LLC wrote: But I would dearly like to have a versioning capability. Me too. Example (real life scenario): there is a samba server for about 200 concurrent connected users. They keep mainly doc/xls files on the server. From time to time they (somehow) currupt their files (they share the files so it is possible) so they are recovered from backup. Having versioning they could be said that if their main file is corrupted they can open previous version and keep working. ZFS snapshots is not solution in this case because we would have to create snapshots for 400 filesystems (yes, each user has its filesystem and I said that there are 200 concurrent connections but there much more accounts on the server) each hour or so. przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Info on OLTP Perf
On Mon, Sep 25, 2006 at 08:37:23AM -0700, Neelakanth Nadgir wrote: We did an experiment where we placed the logs on UFS+DIO and the rest on ZFS. This was a write heavy benchmark. We did not see much gain in performance by doing that (around 5%). I suspect you would be willing to trade 5% for all the benefits of ZFS. Moreover this penalty is for the current version, ZFS can/will get much faster. -neel Neel, I thought of the other solution: the logs on ZFS and rest on UFS+DIO. I suspect that writes on ZFS are faster then on UFS+DIO (in OLTP environment). przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Info on OLTP Perf
On Fri, Sep 22, 2006 at 03:38:05PM +0200, Roch wrote: http://blogs.sun.com/roch/entry/zfs_and_oltp After reading this page and taking into consideration my (not so big) knowledge of ZFS it came to my mind that putting e.g. Oracle on both UFS+DIO _and_ ZFS would be the best solution _at_the_moment_. E.g redo logs and undo tablespace on ZFS (because its COW nature so that all writes to these files will go with full speed) and all the rest database files on UFS+DIO. What do you think ? przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] zpool iostat
On Mon, Sep 18, 2006 at 11:05:07AM -0400, Krzys wrote:
Hello folks, is there any way to get timestamps when doing zpool iostat 1
for example?
Well I did run zpool iostat 60 starting last night and I got some loads
indicating along the way but without a time stamps I cant figure out at
around what time did they happen.
Workaround (how I did it with vmstat):
/usr/bin/vmstat 1 85530 | ./time.pl
where time.pl is perl script:
#!/usr/bin/perl -w
use FileHandle;
STDOUT-autoflush(1);
while ( ) {
chomp $_;
my @Time = localtime();
printf %04d-%02d-%02d %02d:%02d:%02d %-100s\n, 1900 + $Time[5], 1 +
$Time[4], $Time[3], $Time[2], $Time[1], $Time[0], $_;
}
przemol
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Re: [zfs-discuss] Re: Recommendation ZFS on StorEdge 3320 - offtopic
On Thu, Sep 07, 2006 at 12:14:20PM -0700, Richard Elling - PAE wrote: [EMAIL PROTECTED] wrote: This is the case where I don't understand Sun's politics at all: Sun doesn't offer really cheap JBOD which can be bought just for ZFS. And don't even tell me about 3310/3320 JBODs - they are horrible expansive :-( Yep, multipacks are EOL for some time now -- killed by big disks. Back when disks were small, people would buy multipacks to attach to their workstations. There was a time when none of the workstations had internal disks, but I'd be dating myself :-) For datacenter-class storage, multipacks were not appropriate. They only had single-ended SCSI interfaces which have a limited cable budget which limited their use in racks. Also, they weren't designed to be used in a rack environment, so they weren't mechanically appropriate either. I suppose you can still find them on eBay. If Sun wants ZFS to be absorbed quicker it should have such _really_ cheap JBOD. I don't quite see this in my crystal ball. Rather, I see all of the SAS/SATA chipset vendors putting RAID in the chipset. Basically, you can't get a dumb interface anymore, except for fibre channel :-). In other words, if we were to design a system in a chassis with perhaps 8 disks, then we would also use a controller which does RAID. So, we're right back to square 1. Richard, when I talk about cheap JBOD I think about home users/small servers/small companies. I guess you can sell 100 X4500 and at the same time 1000 (or even more) cheap JBODs to the small companies which for sure will not buy the big boxes. Yes, I know, you earn more selling X4500. But what do you think, how Linux found its way to data centers and become important player in OS space ? Through home users/enthusiasts who become familiar with it and then started using the familiar things in their job. Proven way to achieve world domination. ;-)) przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Re: Recommendation ZFS on StorEdge 3320 - offtopic
On Fri, Sep 08, 2006 at 09:41:58AM +0100, Darren J Moffat wrote: [EMAIL PROTECTED] wrote: Richard, when I talk about cheap JBOD I think about home users/small servers/small companies. I guess you can sell 100 X4500 and at the same time 1000 (or even more) cheap JBODs to the small companies which for sure will not buy the big boxes. Yes, I know, you earn more selling X4500. But what do you think, how Linux found its way to data centers and become important player in OS space ? Through home users/enthusiasts who become familiar with it and then started using the familiar things in their job. But Linux isn't a hardware vendor and doesn't make cheap JBOD or multipack for the home user. Linux is used as a symbol. So I don't see how we get from Sun should make cheap home user JBOD (which BTW we don't really have the channel to sell for anyway) to but Linux dominated this way. Home user = tech/geek/enthusiasts who is an admin in job [ Linux ] Home user is using linux at home and is satisfied with it. He/she then goes to job and says Let's install/use it on less important servers. He/she (and management) is again satisfied with it. So lets use it at more important servers ... etc. [ ZFS ] Home user is using ZFS (Solaris) at home (remember easiness and even WEB interface to ZFS operations !,) to keep photos, musics, etc. and is satisfied with it. He/she the goes to his/her job and says I use for a while a fantastic filesystem. Lets use it on less important servers. Ok. Later on Works ok. Let's use on more important . Etc... Yes, I know, a bit naive. But remember that not only Linux spreads this way but also Solaris as well. I guess most of downloaded Solaris CD/DVD are for x86. You as a company attack at high end/midrange level. Let users/admins/fans attack at lower end level. przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Oracle on ZFS
On Fri, Aug 25, 2006 at 06:52:17PM +0200, Daniel Rock wrote: [EMAIL PROTECTED] schrieb: Hi all, Does anybody use Oracle on ZFS in production (but not as a background/testing database but as a front line) ? [ ... ] Robert and Daniel, How did you put oracle on ZFS: - one zpool+ one filesystem - one zpool+ many filesystems - a few zpools + one filesystem on each - a few zpools + many filesystem on each przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Re: Re: Re: zpool status panics server
On Fri, Aug 25, 2006 at 01:21:25PM -0600, Cindy Swearingen wrote: Hi Neal, The ZFS administration class, available in the fall, I think, covers basically the same content as the ZFS admin guide only with extensive lab exercises. You could not give any ZFS class and advertise it as: ZFS is so simple that we don't have any ZFS class !. Just kidding ;-) przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Oracle on ZFS
Hi all, Does anybody use Oracle on ZFS in production (but not as a background/testing database but as a front line) ? I am interesting especially in: - how does it behave after a long time of using it. Becasue COW nature of ZFS I don't know how it influences performance of queries. - general opinion of such pair (ZFS + Oracle) - which version of Oracle przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] ZFS Performance compared to UFS VxFS - offtopic
On Tue, Aug 22, 2006 at 06:15:08AM -0700, Tony Galway wrote: A question (well lets make it 3 really) ??? Is vdbench a useful tool when testing file system performance of a ZFS file system? Secondly - is ZFS write performance really much worse than UFS or VxFS? and Third - what is a good benchmarking tool to test ZFS vs UFS vs VxFS? Are vdbench and SWAT going to be released to the public ? przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Unreliable ZFS backups or....
On Fri, Aug 11, 2006 at 05:25:11PM -0700, Peter Looyenga wrote: I looked into backing up ZFS and quite honostly I can't say I am convinced about its usefullness here when compared to the traditional ufsdump/restore. While snapshots are nice they can never substitute offline backups. And although you can keep quite some snapshots lying about it will consume diskspace, one of the reasons why people also keep offline backups. However, while you can make one using 'zfs send' it somewhat worries me that the only way to perform a restore is by restoring the entire filesystem (/snapshot). I somewhat shudder at the thought of having to restore /export/home this way to retrieve but a single file/directory. To achive that you can combine ZFS snapshots + ZFS send/receive. [ UFS ] - to restore one/two/... files use ufsrestore - to restore entire filesystem use ufsrestore [ ZFS ] - to restore one/two/... files use snapshot(s) - to restore entire filesystem use 'zfs receive' Am I overlooking something here or are people indeed resorting to tools like tar and the likes again to overcome all this? In my opinion ufsdump / ufsrestore was a major advantage over tar and I really would consider it a major drawback if that would be the only way to backup data in such a way where it can be more easily restored. Now in zfs-era :-) it seems we have to change way of thinking about filesystems. Usually system administrators are restoring two things: - particular files - entire filesystems Both are achievable by above combination. What is more important is that zfs-way (restore a file) seems to be easier. :-) przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] DTrace IO provider and oracle
On Tue, Aug 08, 2006 at 04:47:51PM +0200, Robert Milkowski wrote: Hello przemolicc, Tuesday, August 8, 2006, 3:54:26 PM, you wrote: ppf Hello, ppf Solaris 10 GA + latest recommended patches: ppf while runing dtrace: ppf bash-3.00# dtrace -n 'io:::start [EMAIL PROTECTED], ppf args[2]-fi_pathname] = count();}' ppf ... ppf vim ppf /zones/obsdb3/root/opt/sfw/bin/vim 296 ppf tnslsnr none 2373 ppf fsflush none 2952 ppf sched none 9949 ppf ar60run none 13590 ppf RACUST none 39252 ppf RAXTRX none 39789 ppf RAXMTR none 40671 ppf FNDLIBR none 64956 ppf oracle none 2096052 ppf How can I interpret 'none' ? Is it possible to get full path (like in vim) ? I guess Oracle is on ZFS. Ooops ! After your e-mail I realised I should sent it to dtrace-discuss not zfs-discuss ! No ! Oracle is not on zfs. Sorry ! Well right now IO provider won't work properly with ZFS. I guess it would be hard to implement IO provider in ZFS - but maybe not? However you can use syscall provider and monitor pread, pwrite, etc. syscalls. -- Best regards, Robertmailto:[EMAIL PROTECTED] http://milek.blogspot.com ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] DTrace IO provider and oracle
On Tue, Aug 08, 2006 at 11:33:28AM -0500, Tao Chen wrote: On 8/8/06, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: Hello, Solaris 10 GA + latest recommended patches: while runing dtrace: bash-3.00# dtrace -n 'io:::start [EMAIL PROTECTED], args[2]-fi_pathname] = count();}' ... oracle none 2096052 How can I interpret 'none' ? Is it possible to get full path (like in vim) ? Section 27.2.3 fileinfo_t of DTrace Guide explains in detail why you see 'none' in many cases. http://www.sun.com/bigadmin/content/dtrace/d10_latest.pdf or http://docs.sun.com/app/docs/doc/817-6223/6mlkidllf?a=view The execname part can also be misleading, as many I/O activities are asynchronous (including but not limited to Asynchronous I/O), so whatever thread running on CPU may have nothing to do with the I/O that's occuring. This is working as designed and not a problem that limited to ZFS, IMO. Thanks Tao for the doc pointers. I haven't noticed them. przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] DTrace IO provider and oracle
Hello, Solaris 10 GA + latest recommended patches: while runing dtrace: bash-3.00# dtrace -n 'io:::start [EMAIL PROTECTED], args[2]-fi_pathname] = count();}' ... vim /zones/obsdb3/root/opt/sfw/bin/vim 296 tnslsnr none 2373 fsflush none 2952 sched none 9949 ar60run none 13590 RACUST none 39252 RAXTRX none 39789 RAXMTR none 40671 FNDLIBR none 64956 oracle none 2096052 How can I interpret 'none' ? Is it possible to get full path (like in vim) ? Regards przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] zfs list - column width
Hello, because creating/using filesystems in ZFS becoms cheap it is useful now to create/organize filesystems in hierarchy: bash-3.00# zfs list NAME USED AVAIL REFER MOUNTPOINT dns-pool 136K 43.1G 25.5K /dns-pool dns-pool/zones 50K 43.1G 25.5K /dns-pool/zones dns-pool/zones/dns1 24.5K 43.1G 24.5K /dns-pool/zones/dns1 But if I want bigger hierarchy (for sure I will !) 'zfs list' becomes less readable: bash-3.00# zfs create dns-pool/zones/dns1/root bash-3.00# zfs create dns-pool/zones/dns1/local bash-3.00# zfs list NAME USED AVAIL REFER MOUNTPOINT dns-pool 197K 43.1G 25.5K /dns-pool dns-pool/zones 100K 43.1G 25.5K /dns-pool/zones dns-pool/zones/dns1 74.5K 43.1G 25.5K /dns-pool/zones/dns1 dns-pool/zones/dns1/local 24.5K 43.1G 24.5K /dns-pool/zones/dns1/local dns-pool/zones/dns1/root 24.5K 43.1G 24.5K /dns-pool/zones/dns1/root I would like to customise column width to have nicer view of the hierarchy. Wouldn't be good to have some sort of configuration file in which I could set up the column width ? przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] COW question
On Fri, Jul 07, 2006 at 11:59:29AM +0800, Raymond Xiong wrote: It doesn't. Page 11 of the following slides illustrates how COW works in ZFS: http://www.opensolaris.org/os/community/zfs/docs/zfs_last.pdf Blocks containing active data are never overwritten in place; instead, a new block is allocated, modified data is written to it, and then any metadata blocks referencing it are similarly read, reallocated, and written. To reduce the overhead of this process, multiple updates are grouped into transaction groups, and an intent log is used when synchronous write semantics are required.(from http://en.wikipedia.org/wiki/ZFS) IN snapshot scenario, COW consumes much less disk space and is much faster. It says also that updating uberblock is an atomic operations. How is it achieved ? przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] ZFS and Storage
On Wed, Jun 28, 2006 at 03:30:28PM +0200, Robert Milkowski wrote: ppf What I wanted to point out is the Al's example: he wrote about damaged data. Data ppf were damaged by firmware _not_ disk surface ! In such case ZFS doesn't help. ZFS can ppf detect (and repair) errors on disk surface, bad cables, etc. But cannot detect and repair ppf errors in its (ZFS) code. Not in its code but definitely in a firmware code in a controller. As Jeff pointed out: if you mirror two different storage arrays. przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] ZFS and Storage
On Thu, Jun 29, 2006 at 10:01:15AM +0200, Robert Milkowski wrote: Hello przemolicc, Thursday, June 29, 2006, 8:01:26 AM, you wrote: ppf On Wed, Jun 28, 2006 at 03:30:28PM +0200, Robert Milkowski wrote: ppf What I wanted to point out is the Al's example: he wrote about damaged data. Data ppf were damaged by firmware _not_ disk surface ! In such case ZFS doesn't help. ZFS can ppf detect (and repair) errors on disk surface, bad cables, etc. But cannot detect and repair ppf errors in its (ZFS) code. Not in its code but definitely in a firmware code in a controller. ppf As Jeff pointed out: if you mirror two different storage arrays. Not only I belive. There are some classes of problems that even in one array ZFS could help for fw problems (with many controllers in active-active config like Symetrix). Any real example ? przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] ZFS and Storage
On Wed, Jun 28, 2006 at 02:23:32PM +0200, Robert Milkowski wrote: Hello przemolicc, Wednesday, June 28, 2006, 10:57:17 AM, you wrote: ppf On Tue, Jun 27, 2006 at 04:16:13PM -0500, Al Hopper wrote: Case in point, there was a gentleman who posted on the Yahoo Groups solx86 list and described how faulty firmware on a Hitach HDS system damaged a bunch of data. The HDS system moves disk blocks around, between one disk and another, in the background, to optimized the filesystem layout. Long after he had written data, blocks from one data set were intermingled with blocks for other data sets/files causing extensive data corruption. ppf Al, ppf the problem you described comes probably from failures in code of firmware ppf not the failure of disk surface. Sun's engineers can also do some mistakes ppf in ZFS code, right ? But the point is that ZFS should detect also such errors and take proper actions. Other filesystems can't. Does it mean that ZFS can detect errors in ZFS's code itself ? ;-) What I wanted to point out is the Al's example: he wrote about damaged data. Data were damaged by firmware _not_ disk surface ! In such case ZFS doesn't help. ZFS can detect (and repair) errors on disk surface, bad cables, etc. But cannot detect and repair errors in its (ZFS) code. I am comparing firmware code to ZFS code. przemol ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
