Victor Engle wrote:
On 6/20/07, Torrey McMahon <[EMAIL PROTECTED]> wrote:
Also, how does replication at the ZFS level use more storage - I'm
assuming raw block - then at the array level?
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Just to add to the previous comments. In the case where you have a SAN
array providing storage to a host for use with ZFS the SAN storage
really needs to be redundant in the array AND the zpools need to be
redundant pools.
The reason the SAN storage should be redundant is that SAN arrays are
designed to serve logical units. The logical units are usually
allocated from a raid set, storage pool or aggregate of some kind. The
array side pool/aggregate may include 10 300GB disks and may have 100+
luns allocated from it for example. If redundancy is not used in the
array side pool/aggregate and then 1 disk failure will kill 100+ luns
at once.
That makes a lot of sense in configurations where an array is exporting
LUNs built on raid volumes to a set of heterogeneous hosts. If you're
direct connected to a single box running ZFS or a set of boxes running
ZFS you probably want to export something as close to the raw disks as
possible while maintaining ZFS level redundancy. (Like two R5 LUNs in a
ZFS mirror.) Creating a raid set, carving out lots of LUNs and then
handing them all over to ZFS isn't going to buy you a lot and could
cause performance issues. (LUN skew for example.)
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