Necessary changes on HP-UX when changes on SAN-hardware are done

[Stanimir]

Hi,everybody!
I'm new in using SAN with Simmetrix Storage DMX800.The OS is HP-UX 11.0 with PowerPath 3.0.
So I have VG, included native device as physical volume: c27t1d2. There are alternate links, which are connected with this c27t1d2
for load-balancing and failover options.
My question is following:

1. What about if I decide to change anything with hardware configuration, connected with
this PV and this logical device (c27t1d2)
become uncorrect or unusable?
2. What steps I need to do in order to find new logical device, to remove old unusible device (c27t1d2) and to do my VG to include new PV (LVM config changes?). I need also to keep data on this VG when I do this changes.

Thanks,Stan

[Michael Tully]

I don't entirely understand your question. What type of changes did you have in mind for the device(s)? If you wish to remove the LUN you will end up with a corrupted LVM volume group. If you wanted to remove the LUN, take a backup first, trash the LUN, with vgexport, resize it, re-present it to the system, build a new vg/lv/filesystem and restore the data.

[Angus Crome]

Stan,

There are many opportunities for correction;

- You can try dropping the entire volume group, moving the /etc/lvmtab to another filename and running a vgscan (although, this is slightly dangerous, due to potential loss of volumes). The potential for data loss is very slight with a well patches 11.XX system.

- Another possibility is to run an EMC inq and recreate the volume group(s) using the serial number data from that output to match up the volumes (before and after you make your change). This would require doing manual vgimports with all the devices in a volume group (very time consuming).

- You can also export the volume group (vgexport) and then use SAM to get the correct volumes and import them (very easy). However, the first caveat is, make sure you have all the current SAM patches in place. I had one volume group go south on me doing this, and had to recover from (my mandatory tape backup before the change). That was about 400Gb. Finally, to make discovery of various volume groups easier, I generally touch a file in lvol1 of each volume group with the name of that volume group. That way, you can make absolutely sure that you get the right volume groups imported (without having to change all the entries in the fstab).

[Steven E. Protter]

Any changes to san infrastructure should be preceded by a vgexport

If the device names change you will have to vgimport and set up PVLINKS again.

SEP