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Apr
15
awarded  Yearling
Apr
10
revised Is a large RAID-Z array just as bad as a large RAID-5 array?
added 260 characters in body
Apr
10
comment Is a large RAID-Z array just as bad as a large RAID-5 array?
The source is the experience of myself and coworkers across 1000's of ZFS deployments at Nexenta. As for an update -- the rules stand (04/10/15), nothing has changed that makes me want to edit the bullet points, though I WOULD say I wrote those rules without SSD's in mind. The rules are not necessarily the same for SSD's, depending on circumstantial factors. With them you've got some other considerations, too, like HBA bottlenecking.
Sep
24
awarded  Autobiographer
Jul
8
comment zpool import: volume FAULTED with corrupted data, is it possible to save some data?
I suggest zpool import -fFX simply because you've /already/ done -fFn. It might be "safer" to start playing with zdb to determine what, if anything, is wrong with the pool that would kill a normal import. Sometimes this is something silly like missing disk labels (zdb -l <disk> on each disk should help you see if all 4 labels are intact on each disk and are identical).
Jul
8
comment zpool import: volume FAULTED with corrupted data, is it possible to save some data?
Oh and to answer your question, yes. It is extremely likely ALL or nearly all of your data is intact, it is merely a matter of getting around the various potential gotchya's that are preventing the normal method of import from working.
Jul
8
comment zpool import: volume FAULTED with corrupted data, is it possible to save some data?
I'd do it on latest code, but if you have v28 you may have some version of this -- try zpool import -fFX vol4disks8tb
Apr
15
awarded  Yearling
Mar
30
comment ZFS import unable to find any pools
If you tried with -d <disk dev path including partition> and it didn't show up, try everything again but on an illumos OS. If that still can't see it, I'm out of ideas. You may need to engage a data recovery expert if the data has monetary value, or start looking at the code (src.illumos.org) while on the illumos derivative and dtrace'ing the zpool import command to see what path it takes and try to figure out why it can't see your pool.
Mar
28
comment ZFS import unable to find any pools
I don't know that this is the proper forum for this, because the 'answer' to the question involves a lot of trial & error. For now, try 'zpool import -d </dev/path/to/disk>'. -D lists destroyed pools, -d takes an argument of the location of a disk to look at, and can be specified multiple times on the command line (but in your case, only once will be needed as you have but the one disk). See what that does.
Mar
26
comment ZFS checksum errors: what files are affected?
Do you have any snapshots? They often are a culprit for errors showing up even after the offending file is gone.
Mar
26
answered FREENAS: Why isn't mv command instant within a RAIDZ1 volume?
Mar
11
comment ZFS checksum errors: what files are affected?
Oh, and stop making non-redundant pools. That thing has CKSUM errors because there's no ZFS-level redundancy in place, so it can't correct them automatically.
Mar
11
comment ZFS checksum errors: what files are affected?
Run a scrub, it might list off a file once it gets to it on the disk. That is only possible if the damage is actually in the file and not in metadata AND 'scratch' isn't a zvol (if it's a zvol, ZFS has no clue what file structure is inside).
Feb
16
comment ZFS, NFS and Nexenta
So if I understand correctly, the problem appears when you override the defaults so that your r/wsizes are set to 4k? And that this only affects CentOS 6.5? If that's accurate, let me know, so I can try to replicate in lab.
Feb
14
comment ZFS, NFS and Nexenta
Also, for the record, we have 1000's of RHEL/CentOS clients talking to NexentaStor every day and aren't reporting similar problems. Can you tell us more about your environment? Does anything differ between the Debian and CentOS machines, other than the OS? Hardware? Where they're plugged in/network environment? VM vs hardware?
Feb
14
comment ZFS, NFS and Nexenta
It is likely very telling that it is only happening on RHEL/CentOS clients, but I'm afraid that's not a smoking gun for me - nothing jumps to mind. Have you tried asking on a RHEL/CentOS support forum/area? That the problem is not repeatable on Debian would imply the problem is not with Nexenta, but with RHEL/CentOS specifically.
Feb
14
comment ZFS, NFS and Nexenta
What sort of performance do you get on the Debian system?
Feb
8
comment zfs regular read pauses
Status of C-states? And to pre-empt an answer of 'on', turn off C-states. They are a huge killer of performance (for instance, you'll never get full 10Gbe if C-states is on, fun huh?). You can't really (AFAIK) disable them fully in OS. Go into your BIOS, find anything about C-States and disable it. Then find where it talks about power, and set it to 'Performance' or the equivalent. If your CPU is capable of dropping below C1 (or maybe C1E), you're going to feel performance penalties, and at times you wouldn't even expect it.
Feb
6
comment ZFS, NFS and Nexenta
Way more information necessary. What does 'hddisco' say (as this is a Nexenta box), what does 'zpool status' say, what is in 'dmesg', what is the hardware in question, what is the network environment, what are the clients you're testing from, are you sure you're using NFSv3 and not NFSv4 (some clients default to 4), how are you attempting to copy files.