Converting a non-HAST ZFS pool to a HAST pool
Pete French
petefrench at ticketswitch.com
Tue Oct 19 11:49:16 UTC 2010
> Maybe I'm missing something, but how do you guys check this? Both
> gmirror and glabel use only single sector for its metadata, so 1kB in
> total. HAST metadata takes 4kB plus activemap size, which depends on
> provider size.
I checked it by disconnecting one half of the mirror - which
is on a separate machine in my case remember - and then setting
that machine up with hast. Created the hast device and did a 'diskinfo'
on the resulting device. Compared that to a 'diskinfo' on the original
provider.
Here are the results, for the bare disk, the hast device, the
mirrored device, and partition 'a' on the mirrored device. I
wrote a disklabel there when it was UFSA, in case you
were wondering.
diskinfo /dev/da0s1
/dev/da0s1 512 68718411776 134215648 0 16384 16447 255 32
diskinfo /dev/hast/serp0
/dev/hast/serp0 512 68718403584 134215632 0 0
diskinfo /dev/mirror/mysql0
/dev/mirror/mysql0 512 68718410752 134215646 0 0
diskinfo /dev/mirror/mysql0a
/dev/mirror/mysql0a 512 68718402560 134215630 0 8192 8354 255 63
So my current zpool uses /dev/mirror/mysql0a which is 68718402560 bytes,
and when I move to hast I will be using /dev/hast/serp0 which is
68718403584 bytes - i.e. 1024 bytes larger. Note that if it wasn't
for the BSD style disklabel it would be larger, and wouldnt work.
-pete.
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