On 6/17/06, Dale Ghent <[EMAIL PROTECTED]> wrote:
The concept of shifting blocks in a zpool around in the background as
part of a scrubbing process and/or on the order of a explicit command
to populate newly added devices seems like it could be right up ZFS's
alley. Perhaps it could also be done with volume-level granularity.
Off the top of my head, an area where this would be useful is
performance management - e.g. relieving load on a particular FC
interconnect or an overburdened RAID array controller/cache thus
allowing total no-downtime-to-cp-data-around flexibility when one is
horizontally scaling storage performance.
Another good use would be to migrate blocks that are rarely accessed
to slow storage (750 GB drives with RAID-Z) while very active blocks
are kept on fast storage (solid state disk). Presumably writes would
go to relatively fast storage and use idle IO cycles to migrate those
that don't have "a lot" of reads to slower storage. Blocks that are
very active and reside on slow storage could be migrated (mirrored?)
to fast storage.
Presumably fast storage vs. slow storage is based upon measurement of
performance, leading to automatic balancing across the disks.
Mike
--
Mike Gerdts
http://mgerdts.blogspot.com/
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