sean walmsley wrote:
We have a number of Sun J4200 SAS JBOD arrays which we have multipathed using Sun's MPxIO
facility. While this is great for reliability, it results in the /dev/dsk device IDs
changing from cXtYd0 to something virtually unreadable like
"c4t5000C5000B21AC63d0s3".
Since the entries in /dev/{rdsk,dsk} are simply symbolic links anyway, would there be any
problem with adding "alias" links to /devices there and building our zpools on
them? We've tried this and it seems to work fine producing a zpool status similar to the
following:
...
NAME STATE READ WRITE CKSUM
vol01 ONLINE 0 0 0
mirror ONLINE 0 0 0
top00 ONLINE 0 0 0
bot00 ONLINE 0 0 0
mirror ONLINE 0 0 0
top01 ONLINE 0 0 0
bot01 ONLINE 0 0 0
...
Here our aliases are "topnn" and "botnn" to denote the disks in the top and
bottom JBODs.
The obvious question is "what happens if the alias link disappears?". We've tested this,
and ZFS seems to handle it quite nicely by finding the "normal" /dev/dsk link and simply
working with that (although it's more difficult to get ZFS to use the alias again once it is
recreated).
If anyone can think of anything really nasty that we've missed, we'd appreciate
knowing about it. Alternatively, if there is a better supported means of having
ZFS display human-readable device ids we're all ears :-)
Perhaps an MPxIO RFE for "vanity" device names would be in order?
I recently raised RFE CR 6901193 "Need a command to list current usage
of disks, partitions, and slices".
Unfortunately, it's still in triage so probably not yet visible externally.
Part of this RFE relates to a requirement for vanity naming of disks,
although your requirement is a little different. If you are on support,
you should get yourself added to the RFE, together with your precise
requirements as above.
--
Andrew Gabriel
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