On Apr 3, 2010, at 8:00 PM, Tim Cook wrote:
> On Sat, Apr 3, 2010 at 9:52 PM, Richard Elling <richard.ell...@gmail.com>
> wrote:
> On Apr 3, 2010, at 5:56 PM, Tim Cook wrote:
> >
> > On Sat, Apr 3, 2010 at 7:50 PM, Tim Cook <t...@cook.ms> wrote:
> >> Your experience is exactly why I suggested ZFS start doing some "right
> >> sizing" if you will. Chop off a bit from the end of any disk so that
> >> we're guaranteed to be able to replace drives from different
> >> manufacturers. The excuse being "no reason to, Sun drives are always of
> >> identical size". If your drives did indeed come from Sun, their response
> >> is clearly not true. Regardless, I guess I still think it should be done.
> >> Figure out what the greatest variation we've seen from drives that are
> >> supposedly of the exact same size, and chop it off the end of every disk.
> >> I'm betting it's no more than 1GB, and probably less than that. When
> >> we're talking about a 2TB drive, I'm willing to give up a gig to be
> >> guaranteed I won't have any issues when it comes time to swap it out.
> >>
> >>
> > that's what open solaris is doing more or less for some time now.
> >
> > look in the archives of this mailing list for more information.
> > --
> > Robert Milkowski
> > http://milek.blogspot.com
> >
> >
> >
> > Since when? It isn't doing it on any of my drives, build 134, and judging
> > by the OP's issues, it isn't doing it for him either... I try to follow
> > this list fairly closely and I've never seen anyone at Sun/Oracle say they
> > were going to start doing it after I was shot down the first time.
> >
> > --Tim
> >
> >
> > Oh... and after 15 minutes of searching for everything from 'right-sizing'
> > to 'block reservation' to 'replacement disk smaller size fewer blocks' etc.
> > etc. I don't see a single thread on it.
>
> CR 6844090, zfs should be able to mirror to a smaller disk
> http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6844090
> b117, June 2009
> -- richard
>
>
>
> Unless the bug description is incomplete, that's talking about adding a
> mirror to an existing drive. Not about replacing a failed drive in an
> existing vdev that could be raid-z#. I'm almost positive I had an issue post
> b117 with replacing a failed drive in a raid-z2 vdev.
It is the same code.
That said, I have experimented with various cases and I have not found
prediction of tolerable size difference to be easy.
> I'll have to see if I can dig up a system to test the theory on.
Works fine.
# ramdiskadm -a rd1 100000k
/dev/ramdisk/rd1
# ramdiskadm -a rd2 100000k
/dev/ramdisk/rd2
# ramdiskadm -a rd3 100000k
/dev/ramdisk/rd3
# ramdiskadm -a rd4 99900k
/dev/ramdisk/rd4
# zpool create -o cachefile=none zwimming raidz /dev/ramdisk/rd1
/dev/ramdisk/rd2 /dev/ramdisk/rd3
# zpool status zwimming
pool: zwimming
state: ONLINE
scrub: none requested
config:
NAME STATE READ WRITE CKSUM
zwimming ONLINE 0 0 0
raidz1-0 ONLINE 0 0 0
/dev/ramdisk/rd1 ONLINE 0 0 0
/dev/ramdisk/rd2 ONLINE 0 0 0
/dev/ramdisk/rd3 ONLINE 0 0 0
errors: No known data errors
# zpool replace zwimming /dev/ramdisk/rd3 /dev/ramdisk/rd4
# zpool status zwimming
pool: zwimming
state: ONLINE
scrub: resilver completed after 0h0m with 0 errors on Sat Apr 3 20:08:35 2010
config:
NAME STATE READ WRITE CKSUM
zwimming ONLINE 0 0 0
raidz1-0 ONLINE 0 0 0
/dev/ramdisk/rd1 ONLINE 0 0 0
/dev/ramdisk/rd2 ONLINE 0 0 0
/dev/ramdisk/rd4 ONLINE 0 0 0 45K resilvered
errors: No known data errors
-- richard
ZFS storage and performance consulting at http://www.RichardElling.com
ZFS training on deduplication, NexentaStor, and NAS performance
Las Vegas, April 29-30, 2010 http://nexenta-vegas.eventbrite.com
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