We are a small company that does video editing, among other things, and need a place to keep backup copies of large media files and make it easy to share them.
I've got a box set up with Ubuntu Server and 4 x 500 GB drives. They're currently set up with Samba as four shared folders that Mac/Windows workstations can see fine, but I want a better solution. There are two major reasons for this:
- 500 GB is not really big enough (some projects are larger)
- It is cumbersome to manage the current setup, because individual hard drives have different amounts of free space and duplicated data (for backup). It is confusing now and that will only get worse once there are multiple servers. ("the project is on sever2 in share4" etc)
So, I need a way to combine hard drives in such a way as to avoid complete data loss with the failure of a single drive, and so users see only a single share on each server. I've done linux software RAID5 and had a bad experience with it, but would try it again. LVM looks ok but it seems like no one uses it. ZFS seems interesting but it is relatively "new".
What is the most efficient and least risky way to to combine the hdd's that is convenient for my users?
Edit: The Goal here is basically to create servers that contain an arbitrary number of hard drives but limit complexity from an end-user perspective. (i.e. they see one "folder" per server) Backing up data is not an issue here, but how each solution responds to hardware failure is a serious concern. That is why I lump RAID, LVM, ZFS, and who-knows-what together.
My prior experience with RAID5 was also on an Ubuntu Server box and there was a tricky and unlikely set of circumstances that led to complete data loss. I could avoid that again but was left with a feeling that I was adding an unnecessary additional point of failure to the system.
I haven't used RAID10 but we are on commodity hardware and the most data drives per box is pretty much fixed at 6. We've got a lot of 500 GB drives and 1.5 TB is pretty small. (Still an option for at least one server, however)
I have no experience with LVM and have read conflicting reports on how it handles drive failure. If a (non-striped) LVM setup could handle a single drive failing and only loose whichever files had a portion stored on that drive (and stored most files on a single drive only) we could even live with that.
But as long as I have to learn something totally new, I may as well go all the way to ZFS. Unlike LVM, though, I would also have to change my operating system (?) so that increases the distance between where I am and where I want to be. I used a version of solaris at uni and wouldn't mind it terribly, though.
On the other end on the IT spectrum, I think I may also explore FreeNAS and/or Openfiler, but that doesn't really solve the how-to-combine-drives issue.
Best Answer
LVM is actually quite heavily used. Basically, LVM sits above the hardware (driver) layer. It doesn't add any redundancy or increased reliability (it relies on the underlying storage system to handle reliability). Instead, it provides a lot of added flexibility and additional features. LVM should never see a disk disappear or fail, because the disk failure should be handled by RAID (be it software or hardware). If you lose a disk and can't continue operating (rebuild the RAID, etc), then you should be going to backups. Trying to recover data from an incomplete array should never be needed (if it is, you need to reevaluate your entire design).
Among the things you get with LVM are the ability to easily grow and shrink partitions/filesystems, the ability to dynamically allocate new partitions, the ability to snapshot existing partitions, and mount the snapshots as read only or writable partitions. Snapshots can be incredibly useful, particularly for things like backups.
Personally, I use LVM for every partition (except /boot) on every box I build, and I've been doing so for the past 4 years. Dealing with non-LVM'ed boxes is a huge pain when you want to add or modify your disk layout. If you're using Linux, you definitely want use LVM. [Note: This above stuff on LVM has been updated to better explain what it is and how it fits into the storage equation.]
As for RAID, I don't do servers without raid. With disk prices as cheap as they are, I'd go with RAID1 or RAID10. Faster, simpler, and much more robust.
Honestly though, unless you're wedded to Ubuntu (which I would normally recommend), or if the box is performing other tasks, you might want to look into OpenFiler. It turns your box into a storage appliance with a web interface and will handle all of the RAID/LVM/etc for you, and allow you to export the storage as SMB, NFS, iSCSI, etc. Slick little setup.