[linux-lvm] Volume groups on SAN storage

[Thomas Meller <thomas.meller@gmx.net>]

Hello everybody,

recently (today) I had a problem.

I'm trying to create a HA Cluster for a DCE server.
This is difficult work and sometimes very confusing.

My goal is to make it bootable from a SAN.
So far I managed to install GRUB and boot the machine. The rootfs and the rest can be
mounted.
I found, then, that the SCSI-devices inside one of my volume groups were the wrong ones.

What is special about that is that the same content on a device can be seen on different
SCSI-devices. This is due to some mirroring within the storage sytems. I cannot avoid that.

Now, I have a readonly physical volume inside one of my volume groups. I want to insert the
writeable mirror and get rid of the readonly.
AFAICS this is not possible because I cannot force vgscan to insert a specified SCSI-device.
Of course the VGDA is marked "part of VG xxx" and cannot be written anymore. So it cannot be
imported nor exported or added to a new VG.

Maybe there is an option anywhere how to scan a particular device. 

Does anybody know how to trick LVM?
Is there a hexeditor to patch the VGDA backups to use different /dev/sdXX devices?
And if so, does that help?

I'm using redhat 8.0 and I'm bound to that version.

TIA

Thomas

-- 
Thomas Meller
mailto: thomas.meller@t-systems.ch
mailto: thomas.meller@gmx.net
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