Lots of storage

[ciphergoth]

If I buy one of these: and five of these:

and stick it all together using Linux software RAID, will that work as a relatively cheap (£370) 2TB RAID-5 storage array?

Will it be very noisy, and if so, should I be looking at getting one of these too so I can stick it in another room?



As you might imagine, I'm giving the whole question of backups a lot of thought at the moment...

Comments

[skx.livejournal.com]

It should work as a nice raid system, But if it were me I'd be expecting only 1Tb total.

(md0 = RAID0 on disks 1+2, md1 = RAID0 on disks 3+4, disk 5 as a hot spare.)

In terms of noise I'd assume noisy, just because more than one disk in the same place always seems to be noisy - but I guess it depends what they're plugged into. I've got a couple of desktop machines here and the noise they produce easily masks/exceeds the noise from the external USB drives attached to them.

Having an NSLU2 would be a neat thing to have - but I've not yet used one. I think probably the idea of backups is good but you might want to think about where you're going to place the drives. If they're sat upon the top of a PC in an obvious location then there's nothing stopping them from getting lifted along with the main box ...

[skx.livejournal.com]

For raid0 read raid1.

D'oh.

[ciphergoth.livejournal.com]

I was thinking of RAID-5 rather than RAID-0 - since this is for home rather than business use, I'm not sure it's worth halving the cost efficiency in order to have RAID-0 and hot spares.

Yes, the danger the drive array will be stolen is one thing that makes me think it might be worth placing it elsewhere. However, another option might simply be to bolt it firmly to a sizeable piece of furniture..

[skx.livejournal.com]

The bolting the enclosure might be a good plan, but I'd assume it would still be easy to remove the actual drives from there..

If you keep an eye upon the status, via mdadm, then RAID-5 should be just fine. I'm always a little paranoid when it comes to my data!

[pengshui-master.livejournal.com]

I wouldn't want to run raid5 without a hotspare, as a un expected second failure will render you data lost.

OTOH, I've seen resync trigger drive failures when a drive is marginal.

In your place I'd configure md0 [sda sdb sdc sdd] spare:sde. Which will give you 3xHd disk size.

Since SATA hotswap support seems limited on most of the SATA controllers I've seen . I've tried hotswapping SATA devices before now , and the experience was overall less than satisfactory. It sort of worked but a rebooted tended to be needed anyway.

I suspect this has better reliability than a dual raid1 setup. But I'm too hot to check my gut feeling with hard reasoning.

[juliet]

Definitely agreed re RAID5 & a hotspare. Especially given that it is not uncommon IME for more than one drive to fail at close to the same time (for fairly obvious reasons given that you've bought 'em all at the same time).

I'd certainly recommend either RAID5 + hotspare or mirror-RAID over stripe-RAID, because even if it is only backup, sod's law says...

[skibbley.livejournal.com]

You may also wish to consider RAID6 - our bigger systems use that.

[olethros.livejournal.com]

Curious to know why you'd suggest raid 1 and a hot spare over raid5?

[skx.livejournal.com]

It strikes me that when you have a lot of drives in the same physical location a single problem is liable to affect multiple drives at roughly the same time.

For example vibration, heat, flood damage(!), etc, are both going to be shared across neighbour drives - even if those at the "far side" of the enclosure are OK.

To compensate for that I'd arranage the drives (physically) in a pattern like this:

[md0-1][md1-1][spare][md0-2][md0-3]

(The idea is that adjacent pairs of disks come from different RAID sets - and with this arrangement any two contiguous drives can die without a problem.)

For RAID-5 if you have two drives die at the same time you're toast, regardless of location.

[nikolasco.livejournal.com]

Not just the same physical location, but also the drivers are from same manufacturer and bought at the same time from the same place... It jus seems likely that once one gives up due to foo, they all will.

At home, I've always tried to have enough slots to have completely empty ones between drives.