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Mirror LVM Volumes

Posted on 2008-10-30
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I'm new to LVM so please be gentle with your responses.  I just setup an openSUSE 11 server with a DAS attached via SAS.  I've been "toying" with LVM as I want to be able to easily add storage space when necessary.  This server/DAS will be used for disk-to-disk backups so I'm a little parnoid about in needing to ensure that the data will always available for restores.  The server has hardware mirroingfor the OS with a hot standby HD and the DAS is configured RAID5 with a hot standby.  My question is, is there a way to create two LV's in which one LV is a mirror of the other.  My worries are if LVM "crashes" my data LV, I'd like to be able to recover from a mirror copy.  I've read about LV Snapshot but I don't think that's the answer as my data LV will continuously change/grow.  

Any and all thoughts/suggestions are greatly appreciated!
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Question by:custominet
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Mirroring the LVM will not protect you from a "crached" lvm. Mirroring in LVM is basically having the data on two physical devices and will only protect you from HDD failure.

But when you do any operation on the LVM meta data itself (creating a new LV or resizing another) it will backup that data. In order to restore a broken LVM you would use vgcfgrestore.

But I have been using LVM for 10 years now (starting with HP-UX and moving to Linux) and it is very stable. Red Hat has had it as a default solution since version 4 of there RHEL distribution. I'd be suprised if it crashed your data LV anytime soon.

And you can of course backup your data as usual even if it is on LVM drugs! ;)
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by:custominet
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I guess my main fear is when I go to expand the LV that something may "mess up".  If I"m understanding you correctly, you believe LVM is extremely stable and I shouldn't have issues?  I know there's always the possibility of Mr Murphy stolling throgh town but...  I guess when I do go to expand the LV, I'll stop services and do the old-fashion backup.  It's just that it can grow to several TB of data which could take a while to backup.  Thanks for the feedback.
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by:Rance_Hall
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what about lvm on top of raid?

use raid mirroring and setup two drives to be mirrors of each other, then when the os takes over lvm on the ONE drive.

Then when adding disks, add them to the raid array first, and then add them to the lvm
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