Hans-Joerg Haederli - Sun Switzerland Zurich - Sun Support Services wrote:
Hi colleagues
IHAC who wants to use ZFS with his HDS box. He asks now how he can do
the
following:
- Create ZFS pool/fs on HDS LUNs
- Create Copy with ShadowImage inside HDS
- Disconnect ShadowImage
- Import ShadowImage with ZFS in addition to the existing ZFS pool/fs
I wonder how ZFS is handling this. But it should be no issue.
This question has been asked a few times with no good answers. There are
two underlying issues that I can't square away as I don't have gear to
test with.
1 - ZFS is self consistent but if you take a LUN snapshot then any
transactions in flight might not be completed and the pool - Which you
need to snap in its entirety - might not be consistent. The more LUNs
you have in the pool the more problematic this could get. Exporting the
pool first would probably get around this issue.
2 - If you import LUNs with the same label or ID as a currently mounted
pool then ZFS will .... no one seems to know. For example: I have a pool
on two LUNS X and Y called mypool. I take a snapshot of LUN X & Y,
ignoring issue #1 above for now, to LUN X' and LUN Y' and wait a few
days. I then present LUNs X' and Y' to the host. What happens? Make it
even more complex and present all the LUNs to the host after a reboot.
Do you get different parts of the pool from different LUNs? Does ZFS
say, "What the hell?!??!"
I'd love to have an answer but, again, no gear to test with at this time.
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