Well in the case of migrating from one storage array to an other newer bugger one the LVM migration capability is handy.
Any one who has had to go through the pain of a SAN migration especially to a different SAN vendor will see the value of LVM there. That said that only became stable enough to really trust it on critical infrastructure a few years ago.
The ease in growing a volume on a LUN comes from the fact that LVM volume group can span multiple logical disk partitions and or LUNs although again this really only became stable enough to trust it on critical infrastructure a few years ago as well.
Early on there were many problems with LVM but over the years its matured significantly I've begun to trust it more and more since the release of El6, where under EL5 I absolutely refused to use it on any production box.
Oh and about the disabled flag if that surprised you that you never dealt with volume managers on UNIX because that's an old thing that enterprises like.
For example during the weekends a certain large financial institution I once world for who shall remain nameless on this list use to use that flag for weekend testing on VxFS and VcFS. How we used it was during weekend test we had a separate set of LUNS for production and production QA testing. How this worked is that on the weekend we would unmount the disks with the production version of the app then mount the QA testing disk in their place and load the latest greatest version of the code. To prevent accidental mix ups here's we could have the wring disk mounted we would use the disabled flag on the volume to prevent the possibility of running code which wasn't completely tested or had failed a test during normal business. Then on the weekend we would reverse the flags on the volume so we could ensure that no production data was accidentally lost because of our tests and that we didn't accidentally taint our test results by having a node running the production version on a node during our tests.
I know that sounds complicated but it was actually very easy to script and ensured the reliability of new versions of our mission critical apps during normal business hours.
-- Sent from my HP Pre3
On Dec 10, 2013 19:08, Konstantin Olchanski <olcha...@triumf.ca> wrote:
On Tue, Dec 10, 2013 at 02:43:14PM -0500, Jeff Siddall wrote:
> On 12/09/2013 11:20 PM, ToddAndMargo wrote:
> >>then you absolutely want to be running
> >>them against a snapshot rather than a live FS and LVM makes this easy.
> >
> >Never really cared for LVM. Always used the direct partition approach.
>
> Well, perhaps I can try to convince you some more.
>
> Take another example of upgrading to a bigger disk.
>
You mean "upgrade all the disks in the raid array". Surely you do not run
any important machines with single disks?
--
Konstantin Olchanski
Data Acquisition Systems: The Bytes Must Flow!
Email: olchansk-at-triumf-dot-ca
Snail mail: 4004 Wesbrook Mall, TRIUMF, Vancouver, B.C., V6T 2A3, Canada
