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Message #183411
[Bug 1587686] Re: ZFS: Running ztest repeatedly for long periods of time eventually results in "zdb: can't open 'ztest': No such file or directory"
** Description changed:
+ [SRU Justification][XENIAL]
+
+ Problem: Running ztest repeatedly for long periods of time eventually
+ results in "zdb: can't open 'ztest': No such file or directory"
+
+ [FIX]
+
+ Upstream commit
+ https://github.com/zfsonlinux/zfs/commit/151f84e2c32f690b92c424d8c55d2dfccaa76e51
+
+ [TEST CASE]
+ Without the fix, the ztest will fail after hours of soak testing. With the fix, the issue can't be reproduced.
+
+ [REGRESSION POTENTIAL]
+
+ This fix is an upstream fix and therefore passed the ZFS integration
+ tested. I have also tested this thoroughly with the kernel team ZFS
+ regression tests and not found any issues, so the regression potential
+ is slim to zero.
+
+ ------------------------------------------------------------------
+
+
Problem: Running ztest repeatedly for long periods of time eventually
results in "zdb: can't open 'ztest': No such file or directory"
This bug affects the xenial kernel built-in ZFS as well as the package
zfs-dkms. I don't believe ZFS 0.6.3-stable or 0.6.4-release are
effected, 0.6.5-release seems to have included the offending commit.
Sorry for excessive "Affects" tagging, I'm still new to this and unsure
of the proper packages to report this against and/or how to properly add
the upstream issues/commits.
Upstream bug report: https://github.com/zfsonlinux/zfs/issues/4129
"ztest can occasionally fail because zdb cannot locate the pool after several hours of run time. This appears to be caused be an empty cache file."
How to reproduce: run ztest repeatedly such as a command like this and it will eventually fail:
ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z*
(I have /tmp mounted on tmpfs with a 10G limit but I don't believe this is related in any way, and I've confirmed it's not running out of space)
Upstream fix: https://github.com/zfsonlinux/zfs/commit/151f84e2c32f690b92c424d8c55d2dfccaa76e51
Description: Fix ztest truncated cache file
"Commit efc412b updated spa_config_write() for Linux 4.2 kernels to
truncate and overwrite rather than rename the cache file. This is
the correct fix but it should have only been applied for the kernel
build. In user space rename(2) is needed because ztest depends on
the cache file."
Associated pull request for above commit: https://github.com/zfsonlinux/zfs/pull/4130
I'm not sure why this wasn't backported to release but it's in zfs
master. I've Reproduced this bug on xenial kernels 4.4.0-22-generic,
4.4.0-23-generic, 4.4.0-22-lowlatency, and 4.4.0-23-lowlatency as well
as various xenial master-next builds. After applying the above commit
patch to kernel and building/installing kernel manually, ztest runs
fine. I've also separately tested the commit patch on zfs-dkms package
which also appears to fix the issue. Note however, there may still be
some other outstanding ztest related issues upstream - especially when
preempt and hires timers are used. I'm currently testing more heavily
against lowlatency builds and master-next.
(I'm unsure how to associate this bug with multiple packages but zfs-
dkms and linux-image-* packages both are affected).
P.S. Also of note is
https://github.com/zfsonlinux/zfs/commit/60a4ea3f948f1596b92b666fc7dd21202544edbb
"Fix inverted logic on none elevator comparison" - which interestingly
was signed-off-by canonical but curiously not included in the xenial
kernel or zfs-dkms packages. It was however, backported to 0.6.5-release
upstream.
--
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https://bugs.launchpad.net/bugs/1587686
Title:
ZFS: Running ztest repeatedly for long periods of time eventually
results in "zdb: can't open 'ztest': No such file or directory"
Status in Native ZFS for Linux:
New
Status in linux package in Ubuntu:
Incomplete
Status in zfs-linux package in Ubuntu:
In Progress
Bug description:
[SRU Justification][XENIAL]
Problem: Running ztest repeatedly for long periods of time eventually
results in "zdb: can't open 'ztest': No such file or directory"
[FIX]
Upstream commit
https://github.com/zfsonlinux/zfs/commit/151f84e2c32f690b92c424d8c55d2dfccaa76e51
[TEST CASE]
Without the fix, the ztest will fail after hours of soak testing. With the fix, the issue can't be reproduced.
[REGRESSION POTENTIAL]
This fix is an upstream fix and therefore passed the ZFS integration
tested. I have also tested this thoroughly with the kernel team ZFS
regression tests and not found any issues, so the regression potential
is slim to zero.
------------------------------------------------------------------
Problem: Running ztest repeatedly for long periods of time eventually
results in "zdb: can't open 'ztest': No such file or directory"
This bug affects the xenial kernel built-in ZFS as well as the package
zfs-dkms. I don't believe ZFS 0.6.3-stable or 0.6.4-release are
effected, 0.6.5-release seems to have included the offending commit.
Sorry for excessive "Affects" tagging, I'm still new to this and
unsure of the proper packages to report this against and/or how to
properly add the upstream issues/commits.
Upstream bug report: https://github.com/zfsonlinux/zfs/issues/4129
"ztest can occasionally fail because zdb cannot locate the pool after several hours of run time. This appears to be caused be an empty cache file."
How to reproduce: run ztest repeatedly such as a command like this and it will eventually fail:
ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z*
(I have /tmp mounted on tmpfs with a 10G limit but I don't believe this is related in any way, and I've confirmed it's not running out of space)
Upstream fix: https://github.com/zfsonlinux/zfs/commit/151f84e2c32f690b92c424d8c55d2dfccaa76e51
Description: Fix ztest truncated cache file
"Commit efc412b updated spa_config_write() for Linux 4.2 kernels to
truncate and overwrite rather than rename the cache file. This is
the correct fix but it should have only been applied for the kernel
build. In user space rename(2) is needed because ztest depends on
the cache file."
Associated pull request for above commit: https://github.com/zfsonlinux/zfs/pull/4130
I'm not sure why this wasn't backported to release but it's in zfs
master. I've Reproduced this bug on xenial kernels 4.4.0-22-generic,
4.4.0-23-generic, 4.4.0-22-lowlatency, and 4.4.0-23-lowlatency as well
as various xenial master-next builds. After applying the above commit
patch to kernel and building/installing kernel manually, ztest runs
fine. I've also separately tested the commit patch on zfs-dkms package
which also appears to fix the issue. Note however, there may still be
some other outstanding ztest related issues upstream - especially when
preempt and hires timers are used. I'm currently testing more heavily
against lowlatency builds and master-next.
(I'm unsure how to associate this bug with multiple packages but zfs-
dkms and linux-image-* packages both are affected).
P.S. Also of note is
https://github.com/zfsonlinux/zfs/commit/60a4ea3f948f1596b92b666fc7dd21202544edbb
"Fix inverted logic on none elevator comparison" - which interestingly
was signed-off-by canonical but curiously not included in the xenial
kernel or zfs-dkms packages. It was however, backported to
0.6.5-release upstream.
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References