RAID (part 3)
Since November I've been slowing going through all >600 CDs and ripping them to the lossless FLAC format. I figured if I was going to do it, I was only going to do it once and I might as well do it right. That meant using lossless compression and that meant waiting until it wasn't prohibitively expensive (and least for something as stupid as this) to build a big enough RAID server. Ryan recently completed his similar project and it came to only 127 gigs. I had a lot more CDs so I figured that I'd finish at around 200 to 300 gigs which would be fine. But I hadn't expected that I'd really want to use so much space on the server for backups of the other computers. So I ran out of diskspace before finishing. Damn!
Well, that meant I would need to upgrade my server: add some more disks and go from RAID-1 to RAID-5. Here's what I learned in the process:
Well, that meant I would need to upgrade my server: add some more disks and go from RAID-1 to RAID-5. Here's what I learned in the process:
- 300 gig disks are really cheap now
- You can't go from RAID-1 to RAID-5 without rebuilding it from scratch
- It's really helpful having friends with several hundred gigs of extra space on their servers
- Gigabit Ethernet isn't as fast as you'd think, we were only able to get about 25 MB/s even after tweaking stuff like the frame size.
Personalities : [raid5]Pretty cool, eh?
md0 : active raid5 sda[0] sdd[3] sdc[2] sdb[1]
879171840 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU]
unused devices:
1 Comments:
I was just looking into mdadm and isn't there a 'missing' keyword you can use when building the raid-5 array so that it will make a degraded raid-5 without one of your raid-1 disks, then you can copy data over to the degraded raid-5 array (probably slow and dangerous for your data) and then rebuild by adding in the old raid-1 disk into your raid-5 array... sounds like a lot of trouble, but then again so is tweaking the framesize to copy hundreds of gigs across gigabit ethernet.
found this here on the gentoo forums.
would you mind posting the hardware you use for your raid box? I'm thinking about putting together a raid-5 box myself, both for this purpose and just for general purpose backups (I have a shitload of DV cassettes I need to digitize--comes with having kids I guess) and I do NOT want to get back into the game of trying to figure out what hardware to buy. Thanks! seems like a four- or five-disk raid-5 with 300gb disks would be handy.
-ben
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