[HEADSUP] zfs root pool mounting

[Andriy Gapon]

on 07/12/2012 02:33 Garrett Cooper said the following:
> On Thu, Dec 6, 2012 at 3:08 PM, Garrett Cooper <yanegomi at gmail.com> wrote:
> 
> ...
> 
>> Please document the process to make this work in UPDATING (or at least
>> the fact that this behavior was changed).
>>
>> I'm debugging moving from 9.1-RC2 to CURRENT [as of Tuesday] as it
>> hasn't been as smooth as some of the other upgrades I've done; my
>> zpool -- root -- is setup with a non-legacy mountpoint, I noticed that
>> the cachefile attribute is now "None", etc. I have limited capability
>> with my installed system to debug this because unfortunately there
>> aren't a ton of CURRENT based livecds around to run from (I might look
>> into one of gjb's livecds later on if I get super stuck, but I'm
>> trying to avoid having to do that). gptzfsboot sees the pool with
>> lsdev, but it gets stuck at the mountroot prompt trying to find the
>> filesystem.
>>
>> I'll wipe my /boot/kernel directory and try building/installing the
>> kernel again, but right now I'm kind of dead in the water on the
>> system I'm upgrading :/.

One thing that I recommend to all ZFS users is to make use of boot environments.
They are very easy, very convenient and may save a lot of trouble.
Use either any of the tool available in ports (e.g. sysutils/beadm) or just "do
boot environments" in an ad hoc fashion: snapshot and clone your current / known
good boot+root filesystem and you have a safe environment to fall back to.

>     I thought r236884 requiring a zpool upgrade was the culprit, but
> it wasn't. Still stuck at a mountroot prompt (but now I have gjb's
> liveCD so I can do something about it).
>     Something looks off with zdb -l on CURRENT and STABLE/9. Example
> on my 9-stable box:
> 
> # uname -a
> FreeBSD forza.west.isilon.com 9.1-PRERELEASE FreeBSD 9.1-PRERELEASE #0
> r+2fd0a57: Mon Dec  3 12:02:18 PST 2012
> gcooper at forza.west.isilon.com:/usr/obj/usr/src/sys/FORZA  amd64
> # zdb -l sac2
> cannot open 'sac2': No such file or directory
> # zpool list
> NAME   SIZE  ALLOC   FREE    CAP  DEDUP  HEALTH  ALTROOT
> sac     95G  69.7G  25.3G    73%  1.00x  ONLINE  -
> sac2   232G   117G   115G    50%  1.00x  ONLINE  -

Proper zdb -l usage was described in the "HEADSUP" posting.
It's also available in zdb(8).  zdb -l should be used with disks/partitions/etc,
not with pool names.

>     I'm running into the same behavior before and after I upgraded sac/sac2.
>     My git branch is a lightly modified version of FreeBSD, but
> doesn't contain any ZFS specific changes (I can point you to it if you
> like to look at it).
>     Would appreciate some pointers on what to do next.

Try to get a working environment (using livecd, another disk, backups, etc), try
to follow the original instructions.

-- 
Andriy Gapon