[zfs-fuse] zfs-fuse continues to be a superior recovery alternative to ZoL (Was: Fwd: "zfs rollback" hanged -- what to do?)

[Durval Menezes]

Hello Z-F folks,

Cross-posting here in case anyone's interested.

Cheers,
--
Durval.

---------- Forwarded message ----------
Date: Sun, Dec 14, 2014 at 4:05 PM
Subject: Re: "zfs rollback" hanged -- what to do?
To: "zfs-***@zfsonlinux.org" <zfs-***@zfsonlinux.org>

Hello,

Just tried to rollback a snapshot here (EL6 clone with kernel

2.6.32-504.1.3.el6.x86_64 and ZFS 0.6.3-1.1 installed from the ZFS repo),

zfs rollback

Checked with "zpool iostat pool2014070601": exactly zero I/O for more

than half an hour.

The process shows as "D" in ps, which AFAIK means it's blocked in

uninterruptable wait for I/O.

Any recommendations besides stopping whatever's possible to stop and then

hard-resetting the machine?

No alternatives offered, so I proceeded as above and then imported the pool
and tried to rollback again, with the same result: zfs rollback process in
a neverending block at 'D' state.

Hard reset again, but this time I moved the disk to another machine where I
have zfs-fuse 0.7.0 installed: zfs-fuse imported the pool and processed the
rollback with no issues, in much less time than I'm taking to type this.

Seems zfs-fuse is still a very viable option for recovery, as long as one
keeps his/her pools in a version zfs-fuse can handle (v26, I think).

Crossposting to the zfs-fuse list on this, in case folks there are
interested.
Cheers,
--
Durval.

[Gordan Bobic]

That means there is clearly a bug in ZoL that isn't in zfs-fuse. I don't
suppose you happen to have gathered any data that might provide insight
exactly where the bug might be?

Post by Durval Menezes
Hello Z-F folks,
Cross-posting here in case anyone's interested.
Cheers,
--
Durval.
---------- Forwarded message ----------
Date: Sun, Dec 14, 2014 at 4:05 PM
Subject: Re: "zfs rollback" hanged -- what to do?
Hello,

Just tried to rollback a snapshot here (EL6 clone with kernel

2.6.32-504.1.3.el6.x86_64 and ZFS 0.6.3-1.1 installed from the ZFS repo),

Post by Durval Menezes
zfs rollback

Checked with "zpool iostat pool2014070601": exactly zero I/O for more

than half an hour.

The process shows as "D" in ps, which AFAIK means it's blocked in

uninterruptable wait for I/O.

Any recommendations besides stopping whatever's possible to stop and

then hard-resetting the machine?
No alternatives offered, so I proceeded as above and then imported the
pool and tried to rollback again, with the same result: zfs rollback
process in a neverending block at 'D' state.
Hard reset again, but this time I moved the disk to another machine where
I have zfs-fuse 0.7.0 installed: zfs-fuse imported the pool and processed
the rollback with no issues, in much less time than I'm taking to type
this.
Seems zfs-fuse is still a very viable option for recovery, as long as one
keeps his/her pools in a version zfs-fuse can handle (v26, I think).
Crossposting to the zfs-fuse list on this, in case folks there are
interested.
Cheers,
--
Durval.
--
--
To visit our Web site, click on http://zfs-fuse.net/
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[Durval Menezes]

Hi Gordan,

Post by Gordan Bobic
That means there is clearly a bug in ZoL that isn't in zfs-fuse.

It would not have been the first. Pound for pound, ZoL is giving me much
more headaches than zfs-fuse ever did.

Post by Gordan Bobic
I don't suppose you happen to have gathered any data that might provide
insight exactly where the bug might be?

No -- unfortunately, I'm in a hurry today: have a plane to catch in less
than 2h from now, and I'm still packing up.

But perhaps I can try to reproduce it later.

Cheers,
--
Durval.

Post by Gordan Bobic

Post by Durval Menezes
Hello Z-F folks,
Cross-posting here in case anyone's interested.
Cheers,
--
Durval.
---------- Forwarded message ----------
Date: Sun, Dec 14, 2014 at 4:05 PM
Subject: Re: "zfs rollback" hanged -- what to do?
Hello,

Just tried to rollback a snapshot here (EL6 clone with kernel

2.6.32-504.1.3.el6.x86_64 and ZFS 0.6.3-1.1 installed from the ZFS repo),

Post by Durval Menezes
zfs rollback

Checked with "zpool iostat pool2014070601": exactly zero I/O for more

than half an hour.

The process shows as "D" in ps, which AFAIK means it's blocked in

uninterruptable wait for I/O.

Any recommendations besides stopping whatever's possible to stop and

then hard-resetting the machine?
No alternatives offered, so I proceeded as above and then imported the
pool and tried to rollback again, with the same result: zfs rollback
process in a neverending block at 'D' state.
Hard reset again, but this time I moved the disk to another machine where
I have zfs-fuse 0.7.0 installed: zfs-fuse imported the pool and processed
the rollback with no issues, in much less time than I'm taking to type
this.
Seems zfs-fuse is still a very viable option for recovery, as long as one
keeps his/her pools in a version zfs-fuse can handle (v26, I think).
Crossposting to the zfs-fuse list on this, in case folks there are
interested.
Cheers,
--
Durval.
--
--
To visit our Web site, click on http://zfs-fuse.net/
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