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I'm writing a basic media server where people can upload/download my content. I have 8 2TB hard drives where I would like to store their uploaded files. Problem is navigating a file system that I want to be spread across several hard drives, but make it look like it is just one.
If you can think of a approach, please let me know the the upsides and downsides of your approach.
If it matters, I'm running the server on ubuntu 11.10
dougvk
Posted 2012-02-23T21:46:55.033
Reputation: 317
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What you are looking for is RAID. Specifically RAID 0 would "Stripe" data across the disks. However, it is important to realize that if a singe HD fails, ALL data on all disks is lost. It would be better to setup a RAID 5 (which tolerates 1 disk failure) or RAID 6 (which tolerates 2 failures). However, RAID 5 decreases your usable space by 1 disk (so instead of having 16TB of disk, you have 14). RAID 6 costs you 2 disks, so 12 TB.
The disadvantage of RAID 0 is resilience - do not use it. The advantage is performance. You write to two disks at once, so its * essentially* 2x as fast.
The disadvantage of RAID 5 or 6 is that its not quite as fast as raid 0 and the disk costs. The advantage is better performance (compared to no raid) and better resilience.
The disadvantage for all (true) RAID solutions is that is requires hardware, specifically a RAID controller.
There are also software RAID solutions (LVM for Linux, Logical Disk Manager for Windows) if you dont have the hardware. But they will not perform as well as hardware Raid.
Mike M
Posted 2012-02-23T21:46:55.033
Reputation: 730
3Other sources write that software RAID has very little performance impact, and can even outperform hardware RAID because the OS has better control over how data is stored. – user1686 – 2012-02-23T22:03:46.247
For RAID 1 the reads are faster, but the writes are the same. – Scott Chamberlain – 2012-02-23T22:11:23.427
6This answer has a lot of half-truths and draws a lot of conclusions that simply aren't true. – Garrett – 2012-02-23T22:29:04.183
"The disadvantage of RAID 1 is resilience"--don't you mean RAID 0? RAID 1 (mirroring) allows you to lose a disk and still have your data intact. (With software RAID1, you can actually specify as many mirrors as you want.) Also, LVM is not RAID. Linux's built-in software raid solution is mdadm. – rob – 2012-02-24T01:51:11.347
I's sorry, you guys are correct. I wrote this rather hastily. Raid 0 is what i was discussion (not RAID 1). Thanks for the correction. As far as performance on software RAID, you could be right, new to me – Mike M – 2012-02-24T14:24:57.083
@MikeM: looks better now, although LVM is still not RAID, and you might want to incorporate grawity's performance discussion into your answer. It might also be worth mentioning that RAID5 is not very reassuring with large disks because a second disk could fail while waiting for a replacement or during rebuild, even if you have a hot spare. – rob – 2012-02-29T01:11:53.760
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While you'll need a seperate boot partition, you can use LVM and have a volume group that consists of volumes on all the drives.
If you already have the drives formatted, look at greyhole, which is a linux clone of WHS's drive extender. I'd actually prefer this in this scenario since it seems to be easier to work with, and is more flexible in some ways than LVM
Journeyman Geek
Posted 2012-02-23T21:46:55.033
Reputation: 119 122
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To complement the other answers already posted.
I have been using MHDDFS for 10+ years now. I believe that it has some performance issues as discussed on damek but it just creates a virtual volume out of your existing mounts, super simple for me.
Once installed it is just single line in /etc/fstab:
mhddfs#/mnt/hdd1,/mnt/hdd2,/mnt/hdd3 /mnt/virtual fuse defaults,allow_other 0 0
Munkymorgy
Posted 2012-02-23T21:46:55.033
Reputation: 261
possible duplicate of Windows 7 32-bit: format/combine two physical hard disks as a single partition and this
– Mokubai – 2012-02-23T21:50:34.247What OS is the computer? it matters on what you solutions there are. – Scott Chamberlain – 2012-02-23T21:55:52.883
dougvk: which OS are you talking about? *nix or win? – Baarn – 2012-02-23T21:55:56.567
I'm on ubuntu linux 11.10 – dougvk – 2012-02-23T22:17:04.777