Archive for the ‘RAID Array’ Category

RAID5 Array Setup on Gentoo using mdadm and recovery

Monday, July 20th, 2009

RAID is all set up and working! Finally! Very happy with it.

Sorry, this is going to look a lot of rubbish to most people, but here’s how I got my RAID to work and the diag output!

I’m pretty sure it’d be useful to someone.

If you don’t find the below interesting, I think you’d like this at least:

RAID as seen from Windows XP

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RAID Array – 2

Tuesday, July 14th, 2009

Well, all the bits finally turned up! I haven’t actually much yet apart from making a few decisions, and taking a few pictures:

  • Can’t run my backup on Windows XP x86 – it doesn’t support more than 2TiB, so looking at a second Linux box. For the moment, my backups are going on the 3 separate 1TB drives I already have.
  • XFS seems great, but doesn’t care about bad blocks. Similar with JFS, although I haven’t been able to find out details. EXT3 seems the best bet, but if the FS goes over 8TiB, I’m going to have trouble
  • Software RAID is better than hardware in some terms – specifically in diagnosis. You can actually check temperature and SMART status per drive.
  • oh, and with hardware, you can’t span an array across multiple controllers
  • There’s a way to automatically check for Bad Blocks – see here
  • MDRaid seems to be the best way for software RAID
  • Fill all the drives with data, and randomly corrupt sdX and mdX, see if it can cope – and randomly remove one drive, see what happens

Ok, on with the geek pr0n. Enjoy some pictures of what I’ve got so far. Very impressed with the case too actually!

RAID Array

Saturday, July 11th, 2009

Well, I finally did it. I’ve just bought 6,000GB of Western Digital Hard drives, a massive case and am finally planning to set up my fairly massive RAID!

I’ve spent a lot of time weighing up whether to spend (literally) hundreds of pounds on a Hardware RAID with all the nice nobbly bits, or to use Software RAID, what type of RAID to use, how to get all the hardware in there, whether its possible to extend a RAID easily without losing data, it’s been one hell of a battle.

Along with help from my friends Rich and Thom, who have a slightly better system than what I’ve got an are using hardware, I’ve learnt a hell of a lot. There was also a very useful Slashdot post, Grishankh (216268) gave some excellent advice and I’d really like to thank him for it.

So what have I learnt about hardware and software RAID?

  • RAID IS NOT A BACKUP!
  • Hardware RAID is incredible expensive. If you need two PCI-E cards the same, you’ll want identical cards too.
  • Most hardware RAID cards are actually fake, and use software RAID. Expect to pay through the nose.
  • SMART monitoring on a hardware RAID is fraught with problems. Only some cards can tell you the SMART info.
  • Some hardware RAID cards use proprietary methods to store data, if you card dies and you can’t get another one, you’re possibly screwed.
  • Drives must must MUST be the same size, and preferably the same format to work best.
  • RAID 0 is just for spanning disks, RAID 1 is great but a tad excessive. RAID 5 seems a good, happy medium. If one drive dies, you’ll be fine, but you’ll probably lose data if more than one goes. But you really should have a backup anyway.
  • If you want to extend a drive, you’ll probably have to use a software RAID app like LVM on top anyway, so any benefits of using hardware is kinda lost.

That’s why I’m using software RAID. It’s only a file server, it’s not for anything mission-critical, I’d just like to have a big drive, and a massive back up of it, so I’m planning to set up two software RAIDs in the end, one on Linux, one on Windows. At the moment, I’m just going to be backing up anything important.

In terms of configuration; I’m no expert at this, but it looks like I’m to use:

  • IDE drive as bootup, and another as my (temporary) personal backup
  • 6x 1TB Western Digital drives connected under RAID 5 using
    • mdraid
    • LVM
  • to be honest, unless anyone else has any better ideas, I’ll probably stick with the Gentoo Guide as to setting up RAID.

So what about the hardware? Ok, well obviously I’ve gone for:

Cost a lot less than hardware RAID and should get me set up quite nicely! If anyone has any advice though, I’d love to hear it!

Thanks to all those who helped me =D