On Sun, 11 Oct 2009, Shawn Joy wrote:
So from the zpool man page it seems that it is not possible to put a
single device zpool in a degraded state. Is this correct or does the
fix in Bugs 6565042 and 6322646 change this behavior.
It is true that it is not possible to use the pool if the device that
it is based on is inaccessible or missing. If the device totally
fails or scrambles its data, then the pool is permanently lost.
Also, just want to ensure everyone is on the same page here. There
seems to be some mixed messages in this thread about how sensitive
ZFS is to SAN issues.
Do we all agree that creating a zpool out of one device in a SAN
environment is not recommended. One should always constructs a zfs
mirror or raidz device out of SAN attached devices, as posted in
the ZFS FAQ?
The zpool man page seem to agree with this. Is this correct?
In life there are many things that we "should do" (but often don't).
There are always trade-offs. If you need your pool to be able to
operate with a device missing, then the pool needs to have sufficient
redundancy to keep working. If you want your pool to survive if a
disk gets crushed by a wayward fork lift, then you need to have
redundant storage so that the data continues to be available.
If the devices are on a SAN and you want to be able to continue
operating while there is a SAN failure, then you need to have
redundant SAN switches, redundant paths, and redundant storage
devices, preferably in a different chassis.
Bob
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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