topic Integrity SAS Controller's Integrated Mirrors vs LVM data in Operating System - HP-UX

Integrity SAS Controller's Integrated Mirrors vs LVM data

Francis Noël — Tue, 17 Jun 2008 19:19:18 GMT

Helloooo ITRC Forums !

Today I tried something with an Integrity (rx3600) host that I thought would work, but alas it did not. I am trying to figure out what went wrong, and maybe if I'm lucky fix it.

Here goes :
Had volume group vg01.
vg01 contained two logical volumes.
Volume group vg01 contained only ONE physical volume, used in a "whole disk" fashion.
Physical volume was internal SAS drive.

I rebooted to the EFI shell proceeded to create an IR Mirror though the drvcfg utility. I made sure sure the disk used as the PRIMARY was the one used as a physical volume in vg01.

I then did a "boot vmunix -lm".
I activated vg00 and mounted the vg00 filesystems.

I knew the IR volume would have a different instance number/hardware path/persistent DSF than the single disk I had used as a physical volume in vg01 so I did a vgexport of vg01, an ioscan, an insf, I located the new IR volume's DSF (disk 20) and here is what happened next :

-------------CONSOLE STUFF---------------

# vgimport -v -m /tmp/mapfilevg01 /dev/vg01 /dev/disk/disk20
Beginning the import process on Volume Group "/dev/vg01".
Logical volume "/dev/vg01/lvoracle" has been successfully created
with lv number 1.
Logical volume "/dev/vg01/lvtmp_oracle" has been successfully created
with lv number 2.
vgimport: Volume group "/dev/vg01" has been successfully created.
Warning: A backup of this volume group may not exist on this machine.
Please remember to take a backup using the vgcfgbackup command after activating the volume group.
# strings /etc/lvmtab
/dev/vg00
/dev/disk/disk13_p2
/dev/vg02
/dev/disk/disk18
/dev/vg01
>HH1`
/dev/disk/disk20
# vgchange -a y vg01
vgchange: Warning: Couldn't attach to the volume group physical volume "/dev/disk/disk20":
Illegal byte sequence
vgchange: Couldn't activate volume group "vg01":
Quorum not present, or some physical volume(s) are missing.

vgchange: Warning: couldn't query physical volume "/dev/disk/disk20":
The specified path does not correspond to physical volume attached to
this volume group
vgchange: Warning: couldn't query all of the physical volumes.
# dd if=/dev/disk/disk20
LVMREC014{
>HH0Ñ4{
>HH1`EÜÈ V* EÐ EÙÀPuTTYPuTTYDEFECT0141+0 records in
40+0 records out

----- END CONSOLE STUFF ---------

Sooooo it looks like the LVM info is still there but broken ? Or maybe the disk geometry of the Mirrored drives does not fit what LVM expected to find ?

# diskinfo /dev/rdisk/disk20
SCSI describe of /dev/rdisk/disk20:
vendor: HP
product id: IR Volume
type: direct access
size: 71288832 Kbytes
bytes per sector: 512
# diskinfo /dev/rdisk/disk10
SCSI describe of /dev/rdisk/disk10:
vendor: HP
product id: DG072BB975
type: direct access
size: 71687369 Kbytes
bytes per sector: 512

In the previous output disk20 is IR'd and disk10 is a SAS drive, same model that was used times two to make disk20. Number of bytes are not equal. Would that confuse LVM ? Can it be fixed ? I might try to "break" the mirror and see if the data comes back....

Thoughts and comments appreciated.
I are glad that I not have mirrored boot disk :P~

Re: Integrity SAS Controller's Integrated Mirrors vs LVM data

Francis Noël — Tue, 17 Jun 2008 19:31:47 GMT

yeppers, it is reversible !

Same original disk, after deleting the array in drvcfg. DSF is back to disk9.

# vgexport vg01
vgexport: Volume group "vg01" has been successfully removed.
# mkdir /dev/vg01
# mknod /dev/vg01/group c 64 0x010000
# vgimport -v -m /tmp/mapfilevg01 /dev/vg01 /dev/disk/disk9
Beginning the import process on Volume Group "/dev/vg01".
Logical volume "/dev/vg01/lvoracle" has been successfully created
with lv number 1.
Logical volume "/dev/vg01/lvtmp_oracle" has been successfully created
with lv number 2.
vgimport: Volume group "/dev/vg01" has been successfully created.
Warning: A backup of this volume group may not exist on this machine.
Please remember to take a backup using the vgcfgbackup command after activating the volume group.
# vgchange -a y vg01
Activated volume group
Volume group "vg01" has been successfully changed.

I'm still thinking different geometry confuses LVM......

Re: Integrity SAS Controller's Integrated Mirrors vs LVM data

Francis Noël — Tue, 17 Jun 2008 19:43:26 GMT

I dunno if any of this has been attempted or documented on the forums so in hopes someone might have a use for this I'll post interesting observations.

I'm having fun and I wanna share :)

The drive I had used as the Secondary in the IR Mirror is now a valid PV. Not only that but I imported it into a new VG just for kicks and my lvols and file systems are there and usable.

So the mirror works and does not destroy the data upon deletion of the array. The primary disk is also still usable.

Mirrored form confuses LVM, I think it is because the geometry of the IR Volume is not the same as the original drive used and I suspect LVM records that info in its disk headers. Confirmation of my theory as well as any ideas on how to overcome this are welcome !

Re: Integrity SAS Controller's Integrated Mirrors vs LVM data

Francis Noël — Wed, 25 Jun 2008 17:15:04 GMT

Well it seems it cannot be overcome.

HP Support confirms that creating an IR Mirror after putting data on the disks is not supported.

There were also hints that the Migrate Data option would be removed from the Array Creation Options in upcoming controller firmware releases.