Jef Pearlman wrote:
Hi. I'm looking for the best solution to create an expandable heterogeneous
pool of drives. I think in an ideal world, there'd be a raid version which
could cleverly handle both multiple drive sizes and the addition of new drives
into a group (so one could drop in a new drive of arbitrary size, maintain some
redundancy, and gain most of that drive's capacity), but my impression is that
we're far from there.
Mirroring (aka RAID-1, though technically more like RAID-1+0) in ZFS will do
this.
Absent that, I was considering using zfs and just having a single pool. My main question
is this: what is the failure mode of zfs if one of those drives either fails completely
or has errors? Do I permanently lose access to the entire pool? Can I attempt to read
other data? Can I "zfs replace" the bad drive and get some level of data
recovery? Otherwise, by pooling drives am I simply increasing the probability of a
catastrophic data loss? I apologize if this is addressed elsewhere -- I've read a bunch
about zfs, but not come across this particular answer.
We generally recommend a single pool, as long as the use case permits.
But I think you are confused about what a zpool is. I suggest you look
at the examples or docs. A good overview is the slide show
http://www.opensolaris.org/os/community/zfs/docs/zfs_last.pdf
As a side-question, does anyone have a suggestion for an intelligent way to
approach this goal? This is not mission-critical data, but I'd prefer not to
make data loss _more_ probable. Perhaps some volume manager (like LVM on linux)
has appropriate features?
ZFS, mirrored pool will be the most performant and easiest to manage
with better RAS than a raidz pool.
-- richard
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