[EMAIL PROTECTED] wrote on 02/01/2007 01:17:15 PM:
> The ZFS On-Disk specification and other ZFS documentation describe
> the labeling scheme used for the vdevs that comprise a ZFS pool. A
> label entry contains, among other things, an array of uberblocks,
> one of which will point to the active object set of the pool it is a
> part of at a given instant (according to documentation, the active
> uberblock for a given pool could be located in the uberblock array
> of any vdev participating in the pool at a given instant, and is
> subject to relocation from vdev to vdev as the uberblock for the
> pool is recreated in an update). Recreation of the active uberblock
> would occur, for example, if we took a snapshot of the pool and
> changes were then made anywhere in the pool. Since a new uberblock
> is required in this snapshot scenario, and since it appears that the
> uberblocks are treated as a kind of circular list across vdevs, it
> seems to me that the number of available snapshots we could have of
> a pool at any given instant would be strictly limited to the number
> of available uberblocks in the vdevs of the pool (128 uberblocks per
> vdev, if I have that straight). Is this truly the case or am I
> missing something here ?
>
It is my understanding that during the snapshot uberblock pool change
creation chain the old uberblock is treated as a separate entity and not
tied to the new uberblock list.
I am sure I will be corrected if I am reading the flow wrong.
Thanks,
-Wade
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