[oi-dev] SSD-based pools

[Schweiss, Chip]

On Mon, Sep 29, 2014 at 6:14 PM, Andrew M. Hettinger <
AHettinger at prominic.net> wrote:

> Bob Friesenhahn <bfriesen at simple.dallas.tx.us> wrote on 09/29/2014
> 05:57:26 PM:
>
> > How would ZFS know if the data stored is "incorrect" from the user's
> > perspective?
> >
>
> Presumably because the checksum is wrong.
>

Exactly, if the data is returned incorrect from the SSD ZFS will detect it
via checksum.  It will then rebuild from the raidz1 parity, if that fails
it will return a data read error.

In relation to the original topic, with 163 days uptime, the scratch pool
has had zero checksum errors.  It gets completely rewritten about twice a
week on average.  At its peak usage it was rewritten daily for about 45
days.

root at hcp-iops1:~# uptime
 07:44am  up 163 days 20:57,  1 user,  load average: 0.13, 0.15, 0.16
root at hcp-iops1:~# zpool status scratch
  pool: scratch
 state: ONLINE
  scan: scrub repaired 0 in 7h59m with 0 errors on Sat Sep  6 00:59:21 2014
config:

        NAME                         STATE     READ WRITE CKSUM
        scratch                      ONLINE       0     0     0
          raidz1-0                   ONLINE       0     0     0
            c1t500253855035D1B1d0s0  ONLINE       0     0     0
            c1t500253855035D12Fd0s0  ONLINE       0     0     0
            c1t500253855035D114d0s0  ONLINE       0     0     0
            c1t500253855035D10Ed0s0  ONLINE       0     0     0
            c1t500253855035D109d0s0  ONLINE       0     0     0
          raidz1-1                   ONLINE       0     0     0
            c1t500253855035D1C1d0s0  ONLINE       0     0     0
            c1t500253855035D1C0d0s0  ONLINE       0     0     0
            c1t500253855035D1BFd0s0  ONLINE       0     0     0
            c1t500253855035D1BEd0s0  ONLINE       0     0     0
            c1t500253855035D1B5d0s0  ONLINE       0     0     0
          raidz1-2                   ONLINE       0     0     0
            c1t500253855035D1E3d0s0  ONLINE       0     0     0
            c1t500253855035D1E1d0s0  ONLINE       0     0     0
            c1t500253855035D1C8d0s0  ONLINE       0     0     0
            c1t500253855035D1C6d0s0  ONLINE       0     0     0
            c1t500253855035D1C3d0s0  ONLINE       0     0     0
          raidz1-3                   ONLINE       0     0     0
            c1t500253855035D8C0d0s0  ONLINE       0     0     0
            c1t500253855035D8BDd0s0  ONLINE       0     0     0
            c1t500253855035D1F6d0s0  ONLINE       0     0     0
            c1t500253855035D1E6d0s0  ONLINE       0     0     0
            c1t500253855035D1E5d0s0  ONLINE       0     0     0
          raidz1-4                   ONLINE       0     0     0
            c1t500253855035D8C7d0s0  ONLINE       0     0     0
            c1t500253855035D8C6d0s0  ONLINE       0     0     0
            c1t500253855035D8C3d0s0  ONLINE       0     0     0
            c1t500253855035D8C2d0s0  ONLINE       0     0     0
            c1t500253855035D8C1d0s0  ONLINE       0     0     0
          raidz1-5                   ONLINE       0     0     0
            c1t500253855035E2F6d0s0  ONLINE       0     0     0
            c1t500253855035E2F5d0s0  ONLINE       0     0     0
            c1t500253855035E2ECd0s0  ONLINE       0     0     0
            c1t500253855035E2EBd0s0  ONLINE       0     0     0
            c1t500253855035E2D7d0s0  ONLINE       0     0     0
          raidz1-6                   ONLINE       0     0     0
            c1t500253855035F484d0s0  ONLINE       0     0     0
            c1t500253855035F483d0s0  ONLINE       0     0     0
            c1t500253855035F480d0s0  ONLINE       0     0     0
            c1t500253855035F472d0s0  ONLINE       0     0     0
            c1t500253855035F46Fd0s0  ONLINE       0     0     0
          raidz1-7                   ONLINE       0     0     0
            c1t5002538550363742d0s0  ONLINE       0     0     0
            c1t500253855036373Ed0s0  ONLINE       0     0     0
            c1t50025385503633BDd0s0  ONLINE       0     0     0
            c1t5002538550363164d0s0  ONLINE       0     0     0
            c1t500253855035F489d0s0  ONLINE       0     0     0
          raidz1-8                   ONLINE       0     0     0
            c1t500253855036378Ad0s0  ONLINE       0     0     0
            c1t5002538550363789d0s0  ONLINE       0     0     0
            c1t5002538550363786d0s0  ONLINE       0     0     0
            c1t500253855036374Cd0s0  ONLINE       0     0     0
            c1t500253855036374Bd0s0  ONLINE       0     0     0
          raidz1-9                   ONLINE       0     0     0
            c1t500253855035D1F4d0s0  ONLINE       0     0     0
            c1t500253855035D1ECd0s0  ONLINE       0     0     0
            c1t500253855035D1E2d0s0  ONLINE       0     0     0
            c1t500253855035D1DAd0s0  ONLINE       0     0     0
            c1t500253855035D1B2d0s0  ONLINE       0     0     0
          raidz1-10                  ONLINE       0     0     0
            c1t500253855035D12Dd0s0  ONLINE       0     0     0
            c1t500253855035D8C8d0s0  ONLINE       0     0     0
            c1t500253855035D8C5d0s0  ONLINE       0     0     0
            c1t500253855035D8C4d0s0  ONLINE       0     0     0
            c1t500253855035D1F8d0s0  ONLINE       0     0     0
          raidz1-11                  ONLINE       0     0     0
            c1t5002538550363793d0s0  ONLINE       0     0     0
            c1t500253855035E2DBd0s0  ONLINE       0     0     0
            c1t500253855035E2DAd0s0  ONLINE       0     0     0
            c1t500253855035E2D9d0s0  ONLINE       0     0     0
            c1t500253855035D12Ed0s0  ONLINE       0     0     0
        spares
          c1t5002538550363794d0s0    AVAIL
          c1t5002538550363797d0s0    AVAIL
          c1t500253855035E2D8d0s0    AVAIL

errors: No known data errors
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://openindiana.org/pipermail/oi-dev/attachments/20140930/436a22b8/attachment-0005.html>