zfs discuss - Oct 2012 - What happens when you rm zpool.cache?

If you rm /etc/zfs/zpool.cache and reboot...  The system is smart enough (at
least in my case) to re-import rpool, and another pool, but it didn''t
figure out to re-import some other pool.

How does the system decide, in the absence of rpool.cache, which pools
it''s going to import at boot?
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2012-10-20 16:30, Edward Ned Harvey 
(opensolarisisdeadlongliveopensolaris) ?????:
> If you rm /etc/zfs/zpool.cache and reboot...The system is smart enough
> (at least in my case) to re-import rpool, and another pool, but it
> didn''t figure out to re-import some other pool.
>
> How does the system decide, in the absence of rpool.cache, which pools
> it''s going to import at boot?
>
Should only import those mentioned explicitly as parameters
for zpool import - imports rpool during boot, your another
pool probably from the SMF method you crafted for iscsi.

Nobody asked to import the third pool ;)

//Jim

On 10/20/12 2:30 PM, Edward Ned Harvey 
(opensolarisisdeadlongliveopensolaris) wrote:
>
> How does the system decide, in the absence of rpool.cache, which pools 
> it''s going to import at boot?
>
I guess you are referring to zpool.cache. In that case it will 
automatically import only your rpool.

Follow up question regarding this: is there any way to disable automatic 
import of any non-rpool on boot without any hacks of removing zpool.cache?

Thanks,
Bogdan

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On Sun, 21 Oct 2012 11:40:31 +0200, Bogdan ?ulibrk <bc at default.rs>
wrote:
>On 10/20/12 2:30 PM, Edward Ned Harvey 
>(opensolarisisdeadlongliveopensolaris) wrote:
>>
>> How does the system decide, in the absence of rpool.cache, which pools 
>> it''s going to import at boot?
>>
>
>I guess you are referring to zpool.cache. In that case it will 
>automatically import only your rpool.
>
>Follow up question regarding this: is there any way to disable automatic 
>import of any non-rpool on boot without any hacks of removing zpool.cache?
Perhaps not the answer you were hoping to get: Export the pools that
shouldn''t be imported on boot before the shutdown that precedes it.
>Thanks,
>Bogdan
-- 
Groet, Cordialement, Pozdrawiam, Regards,

Kees Nuyt

On Sun, Oct 21, 2012 at 11:40:31AM +0200, Bogdan ?ulibrk
wrote:
>    Follow up question regarding this: is there any way to disable
>    automatic import of any non-rpool on boot without any hacks of removing
>    zpool.cache?
Certainly.  Import it with an alternate cache file.  You do this by
specifying the `cachefile'' property on the command line.  The
`zpool''
man page describes how to do this.

-- 
-Gary Mills-		-refurb-		-Winnipeg, Manitoba, Canada-

> From: zfs-discuss-bounces at opensolaris.org [mailto:zfs-discuss-
> bounces at opensolaris.org] On Behalf Of Gary Mills
> 
> On Sun, Oct 21, 2012 at 11:40:31AM +0200, Bogdan ?ulibrk wrote:
> >    Follow up question regarding this: is there any way to disable
> >    automatic import of any non-rpool on boot without any hacks of
> removing
> >    zpool.cache?
> 
> Certainly.  Import it with an alternate cache file.  You do this by
> specifying the `cachefile'' property on the command line.  The
`zpool''
> man page describes how to do this.
You can also specify cachefile=none

> From: zfs-discuss-bounces at opensolaris.org [mailto:zfs-discuss-
> bounces at opensolaris.org] On Behalf Of Edward Ned Harvey
> 
> If you rm /etc/zfs/zpool.cache and reboot...  The system is smart enough
(at
> least in my case) to re-import rpool, and another pool, but it
didn''t figure out
> to re-import some other pool.
> 
> How does the system decide, in the absence of rpool.cache, which pools
it''s
> going to import at boot?
So, in this thread, I haven''t yet got the answer that I expect or
believe.  Because, the behavior I observed was:

I did a "zfs send" from one system to another, received onto
/localpool/backups.  Side note, the receiving system has three pools: rpool,
localpool, and iscsipool.  Unfortunately, I sent the zfs properties with it,
including the mountpoint.  Naturally, there was already something mounted on /
and /exports and /exports/home, so the zfs receive failed to mount on the
receiving system, but I didn''t notice that.  Later, I rebooted.

During reboot, of course, rpool mounted correctly on /, but then the system
found the localpool/backups filesystems, and mounted /exports, /exports/home and
so forth.  So when it tried to mount rpool/exports, it failed.  Then, iscsipool
was unavailable, so the system failed to bootup completely.  I was able to login
to console as myself, but I had no home directory, so I su''d to root.

I tried to change the mountpoints of localpool/backups/exports and so forth -
but it failed.  Filesystem is in use, or filesystem busy or something like that.
(Because I logged in, obviously.)  I tried to export localpool, and again
failed.  So I wanted some way to prevent localpool from importing or mounting
next time, although I can''t make it unmount or change mountpoints this
time.

rm /etc/zfs/zpool.cache ; init 6

This time, the system came up, and iscsipool was not imported (as expected.) 
But I was surprised - localpool was imported.

Fortunately, this time the system mounted filesystems in the right order -
rpool/exports was mounted under /exports, and I was able to login as myself, and
export/import / change mountpoints of the localpool filesystems.  One more
reboot just to be sure, and voila, no problem.

Point in question is - After I removed the zpool.cache file, I expected rpool to
be the only pool imported upon reboot.  That''s not what I observed, and
I was wondering how the system knew to import localpool?

Are you sure that the system with failed mounts came up NOT in a
read-only root moment, and that your removal of /etc/zfs/zpool.cache
did in fact happen (and that you did not then boot into an earlier
BE with the file still in it)?

On a side note, repairs of ZFS mount order are best done with a
single-user mode boot (-s as a kernel parameter in GRUB), which
among other things spawns very few programs and keeps your FSes
not busy. Also you (should) get to log in as root directly even
if it normally a "role" account and not a "user" on your
box.

2012-10-22 15:06, Edward Ned Harvey 
(opensolarisisdeadlongliveopensolaris) ?????:
>> From: zfs-discuss-bounces at opensolaris.org [mailto:zfs-discuss-
>> bounces at opensolaris.org] On Behalf Of Edward Ned Harvey
>>
>> If you rm /etc/zfs/zpool.cache and reboot...  The system is smart
enough (at
>> least in my case) to re-import rpool, and another pool, but it
didn''t figure out
>> to re-import some other pool.
>>
>> How does the system decide, in the absence of rpool.cache, which pools
it''s
>> going to import at boot?
>
> So, in this thread, I haven''t yet got the answer that I expect or
believe.  Because, the behavior I observed was:
>
> I did a "zfs send" from one system to another, received onto
/localpool/backups.  Side note, the receiving system has three pools: rpool,
localpool, and iscsipool.  Unfortunately, I sent the zfs properties with it,
including the mountpoint.  Naturally, there was already something mounted on /
and /exports and /exports/home, so the zfs receive failed to mount on the
receiving system, but I didn''t notice that.  Later, I rebooted.
>
> During reboot, of course, rpool mounted correctly on /, but then the system
found the localpool/backups filesystems, and mounted /exports, /exports/home and
so forth.  So when it tried to mount rpool/exports, it failed.  Then, iscsipool
was unavailable, so the system failed to bootup completely.  I was able to login
to console as myself, but I had no home directory, so I su''d to root.
>
> I tried to change the mountpoints of localpool/backups/exports and so forth
- but it failed.  Filesystem is in use, or filesystem busy or something like
that.  (Because I logged in, obviously.)  I tried to export localpool, and again
failed.  So I wanted some way to prevent localpool from importing or mounting
next time, although I can''t make it unmount or change mountpoints this
time.
>
> rm /etc/zfs/zpool.cache ; init 6
>
> This time, the system came up, and iscsipool was not imported (as
expected.)  But I was surprised - localpool was imported.
>
> Fortunately, this time the system mounted filesystems in the right order -
rpool/exports was mounted under /exports, and I was able to login as myself, and
export/import / change mountpoints of the localpool filesystems.  One more
reboot just to be sure, and voila, no problem.
>
> Point in question is - After I removed the zpool.cache file, I expected
rpool to be the only pool imported upon reboot.  That''s not what I
observed, and I was wondering how the system knew to import localpool?
>
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> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
>

> From: Jim Klimov [mailto:jimklimov at cos.ru]
> Sent: Monday, October 22, 2012 7:26 AM
> 
> Are you sure that the system with failed mounts came up NOT in a
> read-only root moment, and that your removal of /etc/zfs/zpool.cache
> did in fact happen (and that you did not then boot into an earlier
> BE with the file still in it)?
I''m going to take your confusion and disbelief in support of my
confusion and disbelief.  So it''s not that I didn''t understand
what to expect ... it''s that I somehow made a mistake, but I
don''t know what (and I don''t care enough to try reproducing
the same circumstance.)