Thank you for your answers! It's really useful information. On Thu, Jul 10, 2014 at 2:08 PM, Pavel Snajdr <li...@snajpa.net> wrote: > On 07/10/2014 11:35 AM, Pavel Odintsov wrote: >>> Not true, IO limits are working as they should (if we're talking vzctl >>> set --iolimit/--iopslimit). I've kicked the ZoL guys around to add IO >>> accounting support, so it is there. >> >> You can share tests with us? For standard folders like simfs this >> limits works bad in big number of cases > > If you can give me concrete tests to run, sure, I'm curious to see if > you're right - then we'd have something concrete to fix :) > >> >>> How? ZFS doesn't have a limit on number of files (2^48 isn't a limit really) >> >> It's ok when your customer create 1 billion of small files on 10GB VPS >> and you will try to archive it for backup? On slow disk system it's >> really nightmare because a lot of disk operations which kills your >> I/O. > > zfs snapshot <dataset>@<snapname> > zfs send <dataset>@<snapname> > your-file or | ssh backuper zfs recv > <backupdataset> > > That's done on block level. No need to run rsync anymore, it's a lot > faster this way. > >> >>> Why? ZFS send/receive is able to do bit-by-bit identical copy of the FS, >>> I thought the point of migration is to don't have the CT notice any >>> change, I don't see why the inode numbers should change. >> >> Do you have really working zero downtime vzmigrate on ZFS? > > Nope, vzmigrate isn't zero downtime. Due to vzctl/vzmigrate not > supporting ZFS, we're implementing this our own way in vpsAdmin, which > in it's 2.0 re-implementation will go opensource under GPL. > >> >>> How exactly? I haven't seen a problem with any userspace software, other >>> than MySQL default setting to AIO (it fallbacks to older method), which >>> ZFS doesn't support (*yet*, they have it in their plans). >> >> I speaks about MySQL primarily. I have thousands of containers and I >> can tune MySQL for another mode for all customers, it's impossible. > > As I said, this is under development and will improve. > >> >>> L2ARC cache really smart >> >> Yep, fine, I knew. But can you account L2ARC cache usage per customer? >> OpenVZ can it via flag: >> sysctl -a|grep pagecache_isola >> ubc.pagecache_isolation = 0 > > I can't account for caches per CT, but I didn't have any need to do so. > > L2ARC != ARC, ARC is in system RAM, L2ARC is intended to be on SSD for > the content of ARC that is the least significant in case of low memory - > it gets pushed from ARC to L2ARC. > > ARC has two primary lists of cached data - most frequently used and most > recently used and these two lists are divided by a boundary marking > which data can be pushed away in low mem situation. > > It doesn't happen like with Linux VFS cache that you're copying one big > file and it pushes out all of the other useful data there. > > Thanks to this distinction of MRU and MFU ARC achieves far better hitrates. > >> >> But one customer can eat almost all L2ARC cache and displace another >> customers data. > > Yes, but ZFS keeps track on what's being used, so useful data can't be > pushed away that easily, things naturally balance themselves due to the > way how ARC mechanism works. > >> >> I'm not agains ZFS but I'm against of usage ZFS as underlying system >> for containers. We caught ~100 kernel bugs with simfs on EXT4 when >> customers do some strange thinks. > > I haven't encountered any problems especially with vzquota disabled (no > need for it, ZFS has its own quotas, which never need to be recalculated > as with vzquota). > >> >> But ext4 has about few thouasands developers and the fix this issues >> asap but ZFS on Linux has only 3-5 developers which VERY slow. >> Because of this I recommends using ext4 with ploop because this >> solution is rock stable or ZFS with ZVOL's with ext4 because this >> solution if more reliable and more predictable then placing ZFS >> containers on ZFS volumes. > > ZFS itself is a stable and mature filesystem, it first shipped as > production with Solaris in 2006. > And it's still being developed upstream as OpenZFS, that code is shared > between the primary version - Illumos and the ports - FreeBSD, OS X, Linux. > > So what really needs and still is being developed is the way how ZFS is > run under Linux kernel, but with recent release of 0.6.3, things have > gotten mature enough to be used in production without any fears. Of > course, no software is without bugs, but I can say with absolute > certainty that ZFS will never eat your data, the only problem you can > encounter is with the memory management, which is done really > differently in Linux than in ZFS's original habitat - Solaris. > > /snajpa > >> >> >> On Thu, Jul 10, 2014 at 1:08 PM, Pavel Snajdr <li...@snajpa.net> wrote: >>> On 07/10/2014 10:34 AM, Pavel Odintsov wrote: >>>> Hello! >>>> >>>> You scheme is fine but you can't divide I/O load with cgroup blkio >>>> (ioprio/iolimit/iopslimit) between different folders but between >>>> different ZVOL you do. >>> >>> Not true, IO limits are working as they should (if we're talking vzctl >>> set --iolimit/--iopslimit). I've kicked the ZoL guys around to add IO >>> accounting support, so it is there. >>> >>>> >>>> I could imagine following problems for per folder scheme: >>>> 1) Can't limit number of inodes in different folders (but there are >>>> not an inode limit for ZFS like ext4 but bug amount of files in >>>> container could broke node; >>> >>> How? ZFS doesn't have a limit on number of files (2^48 isn't a limit really) >>> >>>> http://serverfault.com/questions/503658/can-you-set-inode-quotas-in-zfs) >>>> 2) Problems with system cache which used by all containers in HWN together >>> >>> This exactly isn't a problem, but a *HUGE* benefit, you'd need to see it >>> in practice :) Linux VFS cache is really dumb in comparison to ARC. >>> ARC's hitrates just can't be done with what linux currently offers. >>> >>>> 3) Problems with live migration because you _should_ change inode >>>> numbers on diffferent nodes >>> >>> Why? ZFS send/receive is able to do bit-by-bit identical copy of the FS, >>> I thought the point of migration is to don't have the CT notice any >>> change, I don't see why the inode numbers should change. >>> >>>> 4) ZFS behaviour with linux software in some cases is very STRANGE >>>> (DIRECT_IO) >>> >>> How exactly? I haven't seen a problem with any userspace software, other >>> than MySQL default setting to AIO (it fallbacks to older method), which >>> ZFS doesn't support (*yet*, they have it in their plans). >>> >>>> 5) ext4 has good support from vzctl (fsck, resize2fs) >>> >>> Yeah, but ext4 sucks big time. At least in my use-case. >>> >>> We've implemented most of vzctl create/destroy/etc. functionality in our >>> vpsAdmin software instead. >>> >>> Guys, can I ask you to keep your mind open instead of fighting with >>> pointless arguments? :) Give ZFS a try and then decide for yourselves. >>> >>> I think the community would benefit greatly if ZFS woudn't be fought as >>> something alien in the Linux world, which I in my experience is what >>> every Linux zealot I talk to about ZFS is doing. >>> This is just not fair. It's primarily about technology, primarily about >>> the best tool for the job. If we can implement something like this in >>> Linux but without having ties to CDDL and possibly Oracle patents, that >>> would be awesome, yet nobody has done such a thing yet. BTRFS is nowhere >>> near ZFS when it comes to running larger scale deployments and in some >>> regards I don't think it will ever match ZFS, just looking at the way >>> it's been designed. >>> >>> I'm not trying to flame here, I'm trying to open you guys to the fact, >>> that there really is a better alternative than you're currently seeing. >>> And if it has some technological drawbacks like these that you're trying >>> to point out, instead of pointing at them as something, which can't be >>> changed and thus everyone should use "your best solution(tm)", try to >>> think of ways how to change it for the better. >>> >>>> >>>> My ideas like simfs vs ploop comparison: >>>> http://openvz.org/images/f/f3/Ct_in_a_file.pdf >>> >>> Again, you have to see ZFS doing its magic in production under a really >>> heavy load, otherwise you won't understand. Any arbitrary benchmarks >>> I've seen show ZFS is slower than ext4, but these are not tuned for such >>> use cases as I'm talking about. >>> >>> /snajpa >>> >>>> >>>> On Thu, Jul 10, 2014 at 12:06 PM, Pavel Snajdr <li...@snajpa.net> wrote: >>>>> On 07/09/2014 06:58 PM, Kir Kolyshkin wrote: >>>>>> On 07/08/2014 11:54 PM, Pavel Snajdr wrote: >>>>>>> On 07/08/2014 07:52 PM, Scott Dowdle wrote: >>>>>>>> Greetings, >>>>>>>> >>>>>>>> ----- Original Message ----- >>>>>>>>> (offtopic) We can not use ZFS. Unfortunately, NAS with something like >>>>>>>>> Nexenta is to expensive for us. >>>>>>>> From what I've gathered from a few presentations, ZFS on Linux >>>>>>>> (http://zfsonlinux.org/) is as stable but more performant than it is >>>>>>>> on the OpenSolaris forks... so you can build your own if you can spare >>>>>>>> the people to learn the best practices. >>>>>>>> >>>>>>>> I don't have a use for ZFS myself so I'm not really advocating it. >>>>>>>> >>>>>>>> TYL, >>>>>>>> >>>>>>> Hi all, >>>>>>> >>>>>>> we run tens of OpenVZ nodes (bigger boxes, 256G RAM, 12cores+, 90 CTs at >>>>>>> least). We've used to run ext4+flashcache, but ext4 has proven to be a >>>>>>> bottleneck. That was the primary motivation behind ploop as far as I >>>>>>> know. >>>>>>> >>>>>>> We've switched to ZFS on Linux around the time Ploop was announced and I >>>>>>> didn't have second thoughts since. ZFS really *is* in my experience the >>>>>>> best filesystem there is at the moment for this kind of deployment - >>>>>>> especially if you use dedicated SSDs for ZIL and L2ARC, although the >>>>>>> latter is less important. You will know what I'm talking about when you >>>>>>> try this on boxes with lots of CTs doing LAMP load - databases and their >>>>>>> synchronous writes are the real problem, which ZFS with dedicated ZIL >>>>>>> device solves. >>>>>>> >>>>>>> Also there is the ARC caching, which is smarter then linux VFS cache - >>>>>>> we're able to achieve about 99% of hitrate at about 99% of the time, >>>>>>> even under high loads. >>>>>>> >>>>>>> Having said all that, I recommend everyone to give ZFS a chance, but I'm >>>>>>> aware this is yet another out-of-mainline code and that doesn't suit >>>>>>> everyone that well. >>>>>>> >>>>>> >>>>>> Are you using per-container ZVOL or something else? >>>>> >>>>> That would mean I'd need to do another filesystem on top of ZFS, which >>>>> would in turn mean I'd add another unnecessary layer of indirection. ZFS >>>>> is a pooled storage like BTRFS is, we're giving one dataset to each >>>>> container. >>>>> >>>>> vzctl tries to move the VE_PRIVATE folder around, so we had to add one >>>>> more directory to put the VE_PRIVATE data into (see the first ls). >>>>> >>>>> Example from production: >>>>> >>>>> [r...@node2.prg.vpsfree.cz] >>>>> ~ # zpool status vz >>>>> pool: vz >>>>> state: ONLINE >>>>> scan: scrub repaired 0 in 1h24m with 0 errors on Tue Jul 8 16:22:17 >>>>> 2014 >>>>> config: >>>>> >>>>> NAME STATE READ WRITE CKSUM >>>>> vz ONLINE 0 0 0 >>>>> mirror-0 ONLINE 0 0 0 >>>>> sda ONLINE 0 0 0 >>>>> sdb ONLINE 0 0 0 >>>>> mirror-1 ONLINE 0 0 0 >>>>> sde ONLINE 0 0 0 >>>>> sdf ONLINE 0 0 0 >>>>> mirror-2 ONLINE 0 0 0 >>>>> sdg ONLINE 0 0 0 >>>>> sdh ONLINE 0 0 0 >>>>> logs >>>>> mirror-3 ONLINE 0 0 0 >>>>> sdc3 ONLINE 0 0 0 >>>>> sdd3 ONLINE 0 0 0 >>>>> cache >>>>> sdc5 ONLINE 0 0 0 >>>>> sdd5 ONLINE 0 0 0 >>>>> >>>>> errors: No known data errors >>>>> >>>>> [r...@node2.prg.vpsfree.cz] >>>>> ~ # zfs list >>>>> NAME USED AVAIL REFER MOUNTPOINT >>>>> vz 432G 2.25T 36K /vz >>>>> vz/private 427G 2.25T 111K /vz/private >>>>> vz/private/101 17.7G 42.3G 17.7G /vz/private/101 >>>>> <snip> >>>>> vz/root 104K 2.25T 104K /vz/root >>>>> vz/template 5.38G 2.25T 5.38G /vz/template >>>>> >>>>> [r...@node2.prg.vpsfree.cz] >>>>> ~ # zfs get compressratio vz/private/101 >>>>> NAME PROPERTY VALUE SOURCE >>>>> vz/private/101 compressratio 1.38x - >>>>> >>>>> [r...@node2.prg.vpsfree.cz] >>>>> ~ # ls /vz/private/101 >>>>> private >>>>> >>>>> [r...@node2.prg.vpsfree.cz] >>>>> ~ # ls /vz/private/101/private/ >>>>> aquota.group aquota.user b bin boot dev etc git home lib >>>>> <snip> >>>>> >>>>> [r...@node2.prg.vpsfree.cz] >>>>> ~ # cat /etc/vz/conf/101.conf | grep -P "PRIVATE|ROOT" >>>>> VE_ROOT="/vz/root/101" >>>>> VE_PRIVATE="/vz/private/101/private" >>>>> >>>>> >>>>>> _______________________________________________ >>>>>> Users mailing list >>>>>> Users@openvz.org >>>>>> https://lists.openvz.org/mailman/listinfo/users >>>>>> >>>>> >>>>> _______________________________________________ >>>>> Users mailing list >>>>> Users@openvz.org >>>>> https://lists.openvz.org/mailman/listinfo/users >>>> >>>> >>>> >>> >>> _______________________________________________ >>> Users mailing list >>> Users@openvz.org >>> https://lists.openvz.org/mailman/listinfo/users >> >> >> > > _______________________________________________ > Users mailing list > Users@openvz.org > https://lists.openvz.org/mailman/listinfo/users
-- Sincerely yours, Pavel Odintsov _______________________________________________ Users mailing list Users@openvz.org https://lists.openvz.org/mailman/listinfo/users
