LVM and Storage path loss

 
Tarun Jain_1
Advisor

LVM and Storage path loss

After creating a VolumeGroup with one disk, if the FC path is lost to the disk, LVM doesnot respond to the commands "vgdisplay" or "lvdisplay". Even "open()" system call on the logical volume doesn't respond.
Is there any other way to detect that the path to storage is removed ? I want to do the in a script. One way is to set timeout for the commands, but I can not use that because of some constraints.
Thanks in Advance.

Regards,
Tarun
4 REPLIES 4
Torsten.
Acclaimed Contributor

Re: LVM and Storage path loss

I'm not sure, what are you going to do.
If the path to a disk is lost, you see "NO_HW" in ioscan and you have some entries in /var/adm/syslog/syslog.log also. In a FC environment you should use a second path - lvm will use it automatically.

perhaps the command "tdutil" (old name "fcmsutil") is what you are looking for.

Hope this helps!
Regards
Torsten.

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Matti_Kurkela
Honored Contributor

Re: LVM and Storage path loss

"ioscan -fnkCdisk" should show FC disks with lost path as NO_HW. Would this help?

MK
Tarun Jain_1
Advisor

Re: LVM and Storage path loss

I don't want to use I/O scan for this. That command also takes long time.
I want to use only "LVM" commands to detect this. For VxVM, the diskgroup is shown as disabled, so you can figure out immediately that DiskGroup has lost path to its storage. "LVM" commands are blocked in this situation and this is difficult to figure out that, it is because of "lost path" to the disk.
I dont know why the LVM commands are blocked in this condition. These commands should return error or any message stating that Volume group has lost its path to storage.
Torsten.
Acclaimed Contributor

Re: LVM and Storage path loss

most lvm commands are trying to read some information directly from the disk (-header). If the disk is not accessible, timeout is used. that's why it takes some time. again, have a look at "fcmsutil", it provides information from the fc driver, so you can get the status of the fc link, of devices and so on...

Hope this helps!
Regards
Torsten.

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