On Thu, Oct 25, 2012 at 2:25 AM, Jim Klimov jimkli...@cos.ru wrote:
Hello all,
I was describing how raidzN works recently, and got myself wondering:
does zpool scrub verify all the parity sectors and the mirror halves?
Yes. The ZIO_FLAG_SCRUB instructs the raidz or mirror vdev to read
On Wed, Oct 31, 2012 at 6:47 PM, Matthew Ahrens mahr...@delphix.com wrote:
On Thu, Oct 25, 2012 at 2:25 AM, Jim Klimov jimkli...@cos.ru wrote:
Hello all,
I was describing how raidzN works recently, and got myself wondering:
does zpool scrub verify all the parity sectors and the mirror
On 28 October, 2012 - Edward Ned Harvey (opensolarisisdeadlongliveopensolaris)
sent me these 1,0K bytes:
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
boun...@opensolaris.org] On Behalf Of Jim Klimov
I tend to agree that parity calculations likely
are faster (even if
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
boun...@opensolaris.org] On Behalf Of Jim Klimov
I tend to agree that parity calculations likely
are faster (even if not all parities are simple XORs - that would
be silly for double- or triple-parity sets which may use
On 10/26/2012 04:29 AM, Karl Wagner wrote:
Does it not store a separate checksum for a parity block? If so, it
should not even need to recalculate the parity: assuming checksums
match for all data and parity blocks, the data is good.
I could understand why it would not store a checksum for a
On 27/10/12 11:56 AM, Ray Arachelian wrote:
On 10/26/2012 04:29 AM, Karl Wagner wrote:
Does it not store a separate checksum for a parity block? If so, it
should not even need to recalculate the parity: assuming checksums
match for all data and parity blocks, the data is good.
...
Parity is
2012-10-27 20:54, Toby Thain wrote:
Parity is very simple to calculate and doesn't use a lot of CPU - just
slightly more work than reading all the blocks: read all the stripe
blocks on all the drives involved in a stripe, then do a simple XOR
operation across all the data. The actual checksums
On Sat, Oct 27, 2012 at 12:35 PM, Jim Klimov jimkli...@cos.ru wrote:
2012-10-27 20:54, Toby Thain wrote:
Parity is very simple to calculate and doesn't use a lot of CPU - just
slightly more work than reading all the blocks: read all the stripe
blocks on all the drives involved in a stripe,
Does it not store a separate checksum for a parity block? If so, it
should not even need to recalculate the parity: assuming checksums match
for all data and parity blocks, the data is good.
I could understand
why it would not store a checksum for a parity block. It is not really
necessary:
2012-10-26 12:29, Karl Wagner wrote:
Does it not store a separate checksum for a parity block? If so, it
should not even need to recalculate the parity: assuming checksums match
for all data and parity blocks, the data is good.
No, for the on-disk sector allocation over M disks, zfs raidzN
I can only speak anecdotally, but I believe it does.
Watching zpool iostat it does read all data on both disks in a mirrored
pair.
Logically, it would not make sense not to verify all redundant data.
The point of a scrub is to ensure all data is correct.
On 2012-10-25 10:25, Jim Klimov
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
boun...@opensolaris.org] On Behalf Of Karl Wagner
I can only speak anecdotally, but I believe it does.
Watching zpool iostat it does read all data on both disks in a mirrored
pair.
Logically, it would not make sense not to
2012-10-25 15:30, Edward Ned Harvey
(opensolarisisdeadlongliveopensolaris) пишет:
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
boun...@opensolaris.org] On Behalf Of Karl Wagner
I can only speak anecdotally, but I believe it does.
Watching zpool iostat it does read all data on
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
boun...@opensolaris.org] On Behalf Of Jim Klimov
Logically, yes - I agree this is what we expect to be done.
However, at least with the normal ZFS reading pipeline, reads
of redundant copies and parities only kick in if the
On Thu, Oct 25, 2012 at 7:35 AM, Jim Klimov jimkli...@cos.ru wrote:
If scrubbing works the way we logically expect it to, it
should enforce validation of such combinations for each read
of each copy of a block, in order to ensure that parity sectors
are intact and can be used for data
2012-10-25 21:17, Timothy Coalson wrote:
On Thu, Oct 25, 2012 at 7:35 AM, Jim Klimov jimkli...@cos.ru
mailto:jimkli...@cos.ru wrote:
If scrubbing works the way we logically expect it to, it
should enforce validation of such combinations for each read
of each copy of a block, in
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