# Kernel Panic with zfs on root



## narcolepsy (Dec 15, 2011)

Hi, I'd posted in a solved thread, guess it wasn't getting read much so thought I'd post here instead.

I run zfs on root, mirrored on two drives (8.2-RELEASE) and have had a power failure. I have tried dropping to shell from 9.0-RC3 memstick image to try the `# zpool import -F <pool>` trick, but when I do, it says the pool is probably in use and I should try the -f option. When both of these flags are used, or even just the -f on its own I get the failure shown in the picture attached.

Sadly I have learned a great lesson about backups from this (thought my 2-disk mirror would aid stability) but am beginning to think that a single disk with frequent backups would have been more resilient.

Many thanks for any info, and I'll try to get some info from the failing system but it's proving hard since it cannot boot.


 M


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## HarryE (Dec 16, 2011)

What's the real problem? Can't you boot anymore in 8.2? Why the switch to 9.0-RC3? Did you try *zpool import -f yourpool*? Same panic?

Try to disconnect the data cable of one of the HDDs in the mirror and power cycle the computer (no reboot, but power off, pause 5 sec power on). Eventually try the other one, maybe on different controller/port. 

ZFS is pretty good at dealing with power failures. Unless both HDDs are hardware damaged, you should be able to recover your content. I also had a similar problem, but booting failed  due to completely filled drive(s) and the init stopped somewhere along. No kernel panic though.


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## narcolepsy (Dec 16, 2011)

Yes, the switch to 9.0-RC3 was to get the latest version of zfs (v28) so that I could try a transaction rollback import as suggested by phoenix. Thanks for the tip on removing a drive, will try that later.


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## SirDice (Dec 16, 2011)

narcolepsy said:
			
		

> Yes, the switch to 9.0-RC3 was to get the latest version of zfs (v28) so that I could try a transaction rollback import as suggested by phoenix.


8-STABLE also has ZFS v28.


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## narcolepsy (Dec 16, 2011)

Sadly I get the same error with either of the two mirrored devices in the pool connected, so I'm thinking its the same problem written to both disks. I'm worried I'm going to have to nuke them both, unless there's any way to force the sm_size or other.

M


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## gkontos (Dec 16, 2011)

Before nuking them you can try the following:

a) boot from an Openindiana live DVD / memstick and try to import the pool with the -F switch.

b) boot your pool from a different pc 

The reason I suggest the above is because I find very weird the fact that FreeBSD 9-RC3 gives you a kernel panic when you try to import the pool.


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## narcolepsy (Dec 17, 2011)

Hmm, booting from my other 8.2-RELEASE box gave an identical panic (same as 8.2-RELEASE on the troubled box as well as the troubled box booted from 9.0-RC3)

Openindiana doesn't seem to boot correctly from USB, keeps rebooting after 5 minutes of doing seemingly nothing, will try from the .iso (need to install a cd-drive).

Will keep plugging away at this but all the signs are looking negative.


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## narcolepsy (Dec 18, 2011)

Hello again, do you have any info on running a zpool import inside openindiana? I have tried the same commands `# zpool import -F zroot` and it just claims there is no pool of that name.

When I try to get a list of the available pools I get the following problem:


```
jack@openindiana:~$ sudo zpool import
Assertion failed: rn->rn_nozpool == B_FALSE, file ../common/libzfs_import.c, line 1077, function zpool_open_func
```


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## HarryE (Dec 18, 2011)

Try [CMD=]gpart show[/CMD] and [CMD=]gpart recover[/CMD]
as in http://forums.freebsd.org/showthread.php?t=27840


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## narcolepsy (Dec 19, 2011)

There are no gpart errors to be fixed on either disk...thanks for the tip though.


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## narcolepsy (Jan 31, 2012)

Thanks a lot for all the tips folks but I managed to get the disk readable by using `# zpool import -f -o readonly=on zroot`

From there I can recover data then will wipe and update to 9.0-RELEASE.

Cheers again


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