Linux LVM - Is It Ready for Prime Time?

Deagol asks: "I'd like to replace our aging IBM server with a commodity solution (Linux, 3Ware cards, and lots of IDE drives). The main reason is price (the cost of 5 36GB SCSI disks for this sucker -- one of which died today -- could pay for the replacement server with 2TB of usable space after RAID-5. Being a huge fan of AIX's LVM,I've recently been playing with the Linux version of LVM. It's got all the right features (and even the ability to shrink logical volumes, a feature which AIX 4.3.3 doesn't have!), though the commands aren't as polished as the AIX counterparts. The big question for me is, will it stand up and be stable under heavy load, like the IBM does? Is anyone running Linux LVM on a 1TB+, 24/7 production machine?"

Comments

LVM and Redhat 7.3

[cvande]

I built LVM into a RH 7.3 kernel and used it for a DB2 database box. Worked great with the dell 2650 and a 1 tb powervault 220s (raid5 ...aaarrrg...) with the perc3 raid controller. It passed our rather aggressive load testing cyle, ~7 days constant load w/ a variety of different tests, (broken queries, massive table joins, etc, stuff you WOULDN'T want to see in production) and passed with flying colors. It remained in production for a little under a year until we migrated to a Oracle on Linux solution w/o LVM (RedHat AS2.1). I'd do it again in a minute if the implementation called for it.....

just my 2 cents.......

Funny? Flaimbait? -- YOU DECIDE!

[Asprin]

Well, according to SCO, the LVM support in Linux was added by IBM, so it's probably pretty good.




(/me ducks)

Re:Linux LVM

[bobbozzo]

And IBM's EVMS interface can run on top of LVM (http://evms.sourceforge.net/)

So the poster will be able to replace his costly IBM hardware with free IBM software. If that's not ironic, I don't know what is.

Linux LVM just works for me

[linkages]

I have been using LVM on my workstation and just about every machine that I have built in the past 2 years. I also use AIX everyday and agree that the LVM is very robust but I prefer the simplicity of the linux LVM.I recently built a box with software raid 0 and made the whole thing on physical volume and have had zero problems. I have also user the LVM to migrate date from one dist to another without any problems. Oh and did I mention that the LVM howto is really really easy to understand even if you have no previous LVM experiance.

The only thing that scares me about Linux LVM

[devphil]

is that they keep replacing it and reimplementing it in the kernel.

The one linked to in the article (Sistina's) is in 2.4. I'm using it at home, and I like it. We're considering using it at work, but I hear rumours that 2.6 will contain Something Completely Different (Again), which annoys me.

Re:Could someone explain to me?

[Deagol]

LVM gives you a nice layer of abstraction over the disk "device" layer. You can glob all of your "disks" (called "physical volumes") together into a moldable goo of storage called a "volume group". Physical volumes can be real hard drives, files, MD devices, and even regular disk partitions. A volume group, is sliced up into chunks (known as "physical extents" under linux, and as "physical partitions" under AIX). These chunks are the building blocks you then use to create usable file space with. Within a volume group, you can lump a collection of these chunks into a "logical volume" -- which can be though of like a partition, except it isn't tied to the physical space (hence the descriptor "logical"). Logical volumes can then be used like normal partitions and formatted with the filesystem of your choosing.

The underlying hardware of the replacement box is 16 180GB IDE drives, split between 2 8-port 3Ware cards. Each card is doing RAID-5 with 7 drives, the 8th being a hot spare. I let the hardware manage the redundancy for me.

Linux actually sees 2 1080GB (~1TB) SCSI drives. Using standard methods, I can partition these 2 drives any way you normally can under linux. But that kind of binds my feet.

For example, what if the 500GB filesystem for Group A is full and they're clamoring for more space? Using standard partitioning, I'd have to create another larger filesystem, copy the data over, re-export the space, then finally re-claim the old filesystem. In addition to being a pain in the ass, this would require a down time for the users. However, using LVM, I can simply append more of those "chunks" I mentioned above, without creating a new filesystem, Better yet, I can do this on a live system -- my users won't notice a thing (other than the sudden appearance of new file space).

It's really cool stuff.

I'm still uneasy about the reliability, though. I have no hesitation about resizing on-the-fly with hundreds of people running batch jobs on the filesystem under AIX. I haven't seen enough of the Linux LVM in action yet to be that confident of its abilities. If anyone can comment on how Linux NFS and Samba handle having the underlying filesystem resized on-the-fly, I'd love to hear about it.