LSM, AdvFS and Mirroring

From: Dan Cambron <Dan_Cambron_at_tempeqm.sps.mot.com>
Date: 17 Feb 1995 13:14:14 U

                      Subject: Time:
10:28 AM
  OFFICE MEMO LSM, AdvFS and Mirroring Date:
2/17/95
I can't get the following to work, and need to know if it's possible.
I originally wanted to get 4 disks, all advfs, incorporated into one
LSM volume with 2 plexes, and with mirroring enabled between the 2
plexes. Each plex would have 2 of the disks from advfs domains.

+=================================+
| vol01 |
|---------------------------------|
| +-------------+ +-------------+ |
| | plex01 | | plex02 | |
| |-------------| |-------------| |
| | advfs_rz25c | | advfs_rz27c | |
| |-------------| |-------------| |
| | advfs_rz26c | | advfs_rz29c | |
| +-------------+ +-------------+ |
+=================================+

So I tried to walk first and test the concept using 2 partitions from a
single disk (rz28g and rz28h) to build a 2 subdisk plex in a single
volume. It seems that as long as there is a one to one match of advfs
domain devices to LSM volumes it works, but when I pull subdisk rz28h
out of volume vol02 and associate it in the same plex in the other
volume (vol01), there's only 1 LSM device (volume) to map to. ie:

This is ok:
/etc/fdmns/dom1/rz28g -> /dev/vol/rootdg/vol01
/etc/fdmns/dom1/rz28h -> /dev/vol/rootdg/vol02

But after the 2 partitions are combined in a single plex, there is in
vol02 lsm device.:
/etc/fdmns/dom1/rz28g -> /dev/vol/rootdg/vol01
/etc/fdmns/dom1/rz28h -> ?????????????? (vol02 is gone)

LSM sees both devices (subdisks) and reports the full space available
(rz28g + rz28h), but if both advfs devices link to the same volume
(vol01), advfs isn't happy. If I delete one of the advfs device links
in /etc/fdmns/dom1 (like rz28h), then advfs will work, but it only sees
the space on rz28g when a fileset is created. So I can't figure how
to combine multiple advfs partions into a single LSM plex/volume, or
for that matter how to have 2 plexes in a single volume with each plex
containing a single advfs partition. Can it be done, am I way off base
here? Wouldn't be the first time.

If it can't be done, any ideas on how to take advantage of multiple
advfs disks and use lsm to mirror them? This is on OSF/1 V3.0 BTW.

thanks,
dAN
Received on Fri Feb 17 1995 - 15:25:25 NZDT

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