oops I meant mirrorux

[john schiwitz]

oops I meant mirrorux. Thanks.

I've lvextended and lvreduced hundreds of times without any problems.

But the HP support team says I quote:
"

It is critical to ensure that all I/O has been flushed to both copies of
the mirrored logical volume(s) before reducing one of the mirror copies;
the only way to guarantee this is to stop the application, unmount the
filesystems or raw volumes, and deactivate the volume groups that are
affected

NOTE: these steps need to be done on all 9 systems, however they can
be performed one system at a time if desired

a) Confirm mirrors are sync'd before proceeding

# vgdisplay -v (ensure all LVs are sync'd)

b) Ensure the I/O is flushed to each logical volume

Stop application
umount filesystems
deactivate VGs

# vgdisplay (only vg00 should be active)

c) Reduce a mirror from each logical volume


# vgchange -a y /dev/vgxx
# vgdisplay -v

# lvreduce -m 0 /dev/VGxx/LVx /dev/dsk/...
# lvdisplay -v /dev/VGxx/LVx

# vgreduce /dev/VGxx /dev/dsk/... (alternate link)
# vgreduce /dev/VGxx /dev/dsk/... (primary link)
# vgdisplay -v /dev/VG
# strings /etc/lvmtab
"

They say if you really want to do this with your filesystems active you need to buy vxvm.

Just wondered if anyone else had heard this?

[Michael Steele_2 · Accepted solution]

I've heard of LVM's 'vgchange' and synchronization but I've never heard of VXVM's 'vgrecover' sync'ing.

From the LVM 'vgsync' man pages:

"...The synchronization process can be time consuming, depending on the hardware characteristics and the amount of data. Unless disabled, the mirrors within a volume group are synchronized automatically when the volume group is activated by the vgchange -a y command..."

From the VXVM 'vgrecover' man pages:

"...-b Performs recovery operations in the background. With this option, vxrecover runs in the background to attach stale plexes and subdisks, and to resynchronize mirrored volumes and RAID-5 parity. If this is used with -s, volumes are started before recovery begins in the background...."

Here's the vgrecover url:

http://docs.hp.com/cgi-bin/fsearch/framedisplay?top=/hpux/onlinedocs/B9106-90008/B9106-90008_top.html&con=/hpux/onlinedocs/B9106-90008/00/04/491-con.html&toc=/hpux/onlinedocs/B9106-90008/00/04/491-toc.html&searchterms=vxrecover&queryid=20031017-112322

[john schiwitz]

sorry this was a reply to a previous post.

ouch.