# Booting old kernel and zpool.cache



## terminus (Oct 11, 2009)

Hello.

I have a problem using CURRENT on my notebook. System is installed with root file system on ZFS. Today I got problems after performing system update and installing of new kernel - it panics on boot...

Ok, I remember that old kernel is still living in /boot/kernel.old/ and I wanna to boot it. So the steps I perform:

from bootloder prompt

```
unload
load /boot/kernel.old/kernel
load /boot/kernel.old/opensolaris.ko
load /boot/kernel.old/zfs.ko
boot
```

now my system boots, but there is anover problem - it can not find and mount ZFS root file system, and I'm compleatly lost in suggesions how to point it to / filesystem.






I'm been trying to type there anything like

```
zfs:rootvg
zfs:rootvg/
zfs:ad4p3
zfs:/dev/ad4p3
```
no luck for me...

Anower problem is that I can see strange module named

```
/boot/zfs/zpool.cache
```
in the output from lsmod on "bad kernel", but then I load old good kernel and zfs modules I do not see this file in modules list (load /boot/zfs/zpool.cache did'n help).

Any suggesions please? Is it correct that only way to solve this problem is booting from "fixit" CD and mounting of my ZFS root volume?


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## nsayer (Jan 8, 2011)

Has anyone ever solved this? I am currently unable to boot my system and am freaking out.

Is there seriously NO way to load /boot/zfs/zpool.cache from the loader?


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## nsayer (Jan 9, 2011)

I've opened PR kern/153804 about this.


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## nsayer (May 25, 2011)

Thanks to Andriy Gapon, the fix for this is loading the zpool.cache file from the loader. The magic command to do this is

[cmd=]load -t /boot/zfs/zpool.cache /boot/zfs/zpool.cache[/cmd]


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