On Wed, 12 Jan 2011 05:53:40 +0000 John Robinson <john.robinson@xxxxxxxxxxxxxxxx> wrote: > On 12/01/2011 05:32, NeilBrown wrote: > > On Wed, 12 Jan 2011 04:49:35 +0000 John Robinson > > <john.robinson@xxxxxxxxxxxxxxxx> wrote: > [...] > >> Perhaps I can stop the reshape and restart it with the backup file > >> elsewhere. Hmm, I've an SSD I haven't installed yet... Maybe time to > >> give it a wee workout :-) > > > > That should work. > > > > mdadm --stop ... > > copy file > > mdadm --assemble ...... --backup-file=/new/place > > Yup. Not much of an improvement, though; the reshape is now running at > ~10MB/s instead of ~6.5MB/s, so ~27 hours to go instead of ~40 hours. > > iostat tells me the original 3 discs are doing ~120 transactions per > second, reading ~20MB/s and writing ~10MB/s, while the one new disc is > doing ~60 tps, reading nothing (obviously) and writing ~10MB/s and the > backup (SSD) is doing ~45 tps and writing ~20MB/s. ~120tps sounds about > right for 120 seeks, 60 reads and 60 writes, and would explain the > speed, but otherwise this looks odd to me - why are we reading ~60MB/s > in total and writing ~40MB/s? I'd have expected to be reading less than > we're writing. And why are we apparently reading and writing in blocks > of under 512KB per device, when the backup file is 32MB? Is there > something I can tweak to run the reshape in bigger chunks? > sync_speed_min is already 200000... 1/ everything is read twice, once to back it up, once to relocate it. That is unfortunate, but awkward to avoid. 2/ try increasing the stripe_cache_size - it might help. NeilBrown > > Currently running SystemRescueCD 2.0.0, 32-bit kernel 2.6.35 and mdadm > 3.1.4. CPU usage is 2% system, 4% iowait. > > Cheers, > > John. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
