On 17 May, 2010 - Dan Pritts sent me these 1,6K bytes: > On Thu, May 13, 2010 at 06:09:55PM +0200, Roy Sigurd Karlsbakk wrote: > > 1. even though they're 5900, not 7200, benchmarks I've seen show they are > > quite good > > Minor correction, they are 5400rpm. Seagate makes some 5900rpm drives. > > The "green" drives have reasonable raw throughput rate, due to the > extremely high platter density nowadays. however, due to their low > spin speed, their average-access time is significantly slower than > 7200rpm drives. > > For bulk archive data containing large files, this is less of a concern. > > Regarding slow reslivering times, in the absence of other disk activity, > I think that should really be limited by the throughput rate, not the > relatively slow random i/o performance...again assuming large files > (and low fragmentation, which if the archive is write-and-never-delete > is what i'd expect). > > One test i saw suggests 60MB/sec avg throughput on the 2TB drives. > That works out to 9.25 hours to read the entire 2TB. At a conservative > 50MB/sec it's 11 hours. This assumes that you have enough I/O bandwidth > and CPU on the system to saturate all your disks. > > if there's other disk activity during a resilver, though, it turns into > random i/o. Which is slow on these drives.
Resilver does a whole lot of random io itself, not bulk reads.. It reads the filesystem tree, not "block 0, block 1, block 2..". You won't get 60MB/s sustained, not even close. /Tomas -- Tomas Ögren, st...@acc.umu.se, http://www.acc.umu.se/~stric/ |- Student at Computing Science, University of Umeå `- Sysadmin at {cs,acc}.umu.se _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
