On Jul 30, 2012, at 10:20 AM, Roy Sigurd Karlsbakk wrote:
> ----- Opprinnelig melding -----
>> On Mon, Jul 30, 2012 at 9:38 AM, Roy Sigurd Karlsbakk
>> <r...@karlsbakk.net> wrote:
>>>>> Also keep in mind that if you have an SLOG (ZIL on a separate
>>>>> device), and then lose this SLOG (disk crash etc), you will
>>>>> probably
>>>>> lose the pool. So if you want/need SLOG, you probably want two of
>>>>> them in a mirror…
>>>> That's only true on older versions of ZFS. ZFSv19 (or 20?) includes
>>>> the ability to import a pool with a failed/missing log device. You
>>>> lose any data that is in the log and not in the pool, but the pool
>>>> is
>>>> importable.
>>> Are you sure? I booted this v28 pool a couple of months back, and
>>> found it didn't recognize its pool, apparently because of a missing
>>> SLOG. It turned out the cache shelf was disconnected, after
>>> re-connecting it, things worked as planned. I didn't try to force a
>>> new import, though, but it didn't boot up normally, and told me it
>>> couldn't import its pool due to lack of SLOG devices.
>> Positive. :) I tested it with ZFSv28 on FreeBSD 9-STABLE a month or
>> two ago. See the updated man page for zpool, especially the bit about
>> "import -m". :)
> On 151a2, man page just says 'use this or that mountpoint' with import -m, 
> but the fact was zpool refused to import the pool at boot when 2 SLOG devices 
> (mirrored) and 10 L2ARC devices were offline. Should OI/Illumos be able to 
> boot cleanly without manual action with the SLOG devices gone?

No. Missing slogs is a potential data-loss condition. Importing the pool without
slogs requires acceptance of the data-loss -- human interaction.
 -- richard

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