[OpenIndiana-discuss] Simple zfs vs zpool space question.

[John Ryan]

On 13/04/2014 3:13 PM, Jim Klimov wrote:
> On 2014-04-13 01:33, John Ryan wrote:
>> I had a problem once where I was unable to import a pool with a missing
>> log disk. I was unable to recover the pool. Now I mirror the logs
>
> How long ago was that (or, rather, with how old a ZFS version)?
> There was this "feature" of requiring logs for import initially,
> but since then there appeared a command-line flag to allow pool
> import without processing the logs (forfeiting "sync" transactions
> that were only logged there). Probably this would indeed require
> a bit of work in single-user mode (if your pools are imported by
> default with /etc/zfs/zpool.cache) or soon after boot (if another
> pool importing mechanism is used, such as an SMF service), since
> on serious systems the serious decisions are by design delegated
> to humans - even if you can in fact automate the imports with the
> forcing switches in a script on your home rigs, at a risk of some
> conflicts (i.e. relevant on corporate shared storage) or recently
> written data loss (TXG rollback, log ignore, etc.) that you then
> won't be well informed about.
>
> Also note that if the (only) separate log device dies or is removed
> while the pool is up, this should be detected by the OS pretty soon
> and the logs would be written to main pool devices like they are
> on a pool without a log device at all. So the "unprotected" period
> in this case is relatively short, one or a few TXGs.
>
> Of course, by Murphy's law, that is bound to happen rarely - rather,
> your server goes down with a power surge from a lightning, and when
> it comes up - you discover that the log device is toast. Maybe both
> of them mirrored logs ;)
>
> HTH,
> //Jim Klimov
>
>
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I found the option '-m' flag in Solaris 11 man pages, but cannot find it 
in the openIndiana man page.
But 'zpool import --help' shows the '-m' flag. - Is that it?

John