Re: Linux RAID Partition Offset 63 cylinders / 30% performance hit?

2007-12-25 Thread Bill Davidsen
Robin Hill wrote: On Wed Dec 19, 2007 at 09:50:16AM -0500, Justin Piszcz wrote: The (up to) 30% percent figure is mentioned here: http://insights.oetiker.ch/linux/raidoptimization.html That looks to be referring to partitioning a RAID device - this'll only apply to hardware RAID or

Re: raid10 performance question

2007-12-25 Thread Peter Grandi
On Sun, 23 Dec 2007 08:26:55 -0600, Jon Nelson [EMAIL PROTECTED] said: I've found in some tests that raid10,f2 gives me the best I/O of any raid5 or raid10 format. Mostly, depending on type of workload. Anyhow in general most forms of RAID10 are cool, and handle disk losses better and so on.

Re: Raid over 48 disks

2007-12-25 Thread pg_mh
On Wed, 19 Dec 2007 07:28:20 +1100, Neil Brown [EMAIL PROTECTED] said: [ ... what to do with 48 drive Sun Thumpers ... ] neilb I wouldn't create a raid5 or raid6 on all 48 devices. neilb RAID5 only survives a single device failure and with that neilb many devices, the chance of a second

Re: raid10: unfair disk load?

2007-12-25 Thread Bill Davidsen
Richard Scobie wrote: Jon Nelson wrote: My own tests on identical hardware (same mobo, disks, partitions, everything) and same software, with the only difference being how mdadm is invoked (the only changes here being level and possibly layout) show that raid0 is about 15% faster on reads than

Re: Raid over 48 disks

2007-12-25 Thread Bill Davidsen
Peter Grandi wrote: On Wed, 19 Dec 2007 07:28:20 +1100, Neil Brown [EMAIL PROTECTED] said: [ ... what to do with 48 drive Sun Thumpers ... ] neilb I wouldn't create a raid5 or raid6 on all 48 devices. neilb RAID5 only survives a single device failure and with that neilb many devices,

Re: raid10 performance question

2007-12-25 Thread Peter Grandi
On Tue, 25 Dec 2007 19:08:15 +, [EMAIL PROTECTED] (Peter Grandi) said: [ ... ] It's the raid10,f2 *read* performance in degraded mode that is strange - I get almost exactly 50% of the non-degraded mode read performance. Why is that? [ ... ] the mirror blocks have to be read from the

Re: [PATCH 001 of 7] md: Support 'external' metadata for md arrays.

2007-12-25 Thread Andrew Morton
On Fri, 14 Dec 2007 17:26:08 +1100 NeilBrown [EMAIL PROTECTED] wrote: + if (strncmp(buf, external:, 9) == 0) { + int namelen = len-9; + if (namelen = sizeof(mddev-metadata_type)) + namelen = sizeof(mddev-metadata_type)-1; +

Re: [PATCH 004 of 7] md: Allow devices to be shared between md arrays.

2007-12-25 Thread Andrew Morton
On Fri, 14 Dec 2007 17:26:28 +1100 NeilBrown [EMAIL PROTECTED] wrote: + mddev_unlock(rdev-mddev); + ITERATE_MDDEV(mddev, tmp) { + mdk_rdev_t *rdev2; + + mddev_lock(mddev); + ITERATE_RDEV(mddev, rdev2, tmp2)