[SOLVED] Re: "zpool attach" problem
dpchrist at holgerdanske.com
Sun Nov 22 03:50:45 UTC 2020
On 2020-11-21 14:33, Scott Bennett via freebsd-questions wrote:
> Hi David,
> Thanks for your reply. I was about to respond to my own message to say that the
> issue has been resolved, but I saw your reply first. However, I respond below to
> your comments and questions, as well as stating what the problem turned out to be.
I suspect that we all have similar stories. :-)
It sounds like we both have small SOHO networks. My comments below
Spreading two ZFS pools and one GEOM RAID (?) across six HDD's is not
something that I would do or recommend. I also avoid raidzN. I suggest
that you backup, wipe, create one pool using mirrors, and restore.
Apply the GPT partitioning scheme and create one large partition with 1
MiB alignment on each of the six data drives.
When partitioning, some people recommend leaving a non-trivial amount of
unused space at the end of the drive -- say 2% to 5% -- to facilitate
replacing failed drives with somewhat smaller drives. I prefer to use
100% and will buy a pair of identical replacements if faced with that
Label your partitions with names that correlate with your ZFS storage
architecture . Always use the labels for administrative commands;
never use raw device nodes.
(I encrypt the partitions and use the GPT label GELI nodes when creating
the pool, below.)
Create a zpool with three mirrors -- a first mirror of two 2 TB drive
partitions, a second mirror of two 2 TB drive partitions, and a third
mirror of the 3 TB drive and the 4 TB drive partitions. That should
give you about the same available space as your existing raidz2.
Consider buying a spare 4 TB (or two) and putting it on the shelf.
Better yet, connect it to the machine and tell ZFS to use it as a spare.
Buy 4 TB drives going forward.
Adding a solid-state cache device or partition can noticeably improve
read responsiveness (e.g. both sequential and random latency). After
the initial hits, both my Samba and CVS services are snappy.
I expect solid-state log devices would similarly help write performance,
but have not tried it yet.
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