RAID hard drives questions, noobie inside

Scott Salisbury · 10 May 2007 at 12:17

Hey all,

Not sure if this is a general hardware question so mods move as appropriate.

I'm setting up a storage rig, I have 4 SATA hard drives of different sizes and different RPM speeds, ranging from 7200 and 10000. (sizes: 300gb, 200gb, 74gb, 200gb)

My motherboard has 2 onboard sata plugs.

I want to set up all these hard drives as one large joined partition.

Questions:

1. Am I right in thinking that it is RAID0 to join hard drives together as one?
2. If I use a PCI-SATA RAID controller to connect the other 2 hard drives, is it still possible to join these with the onboard SATA controller?

So basically, can I have one joined drive which is 774gb?

semi-pro waster · 10 May 2007 at 12:44

1. You can use Raid0 to join hard drives together but you will only get the size of the smallest drive as it stripes the data across the two (or more) drives that you link. Also they will ideally be the same revision and speed as otherwise you are adding further complications to a storage method that is already more prone to failure due to the requirement of having two drives functioning as one.

2. No, not as far as I am aware, you need them all to be on the same controller.

You can join all the drives together as a JBOD (Just a Bunch Of Disks) array depending on the controller but there is minimal benefit to doing so at best and plenty of downside in that you are again relying on all drives to continue functioning together. My advice is simple, just use each drive as a standalone, it certainly means that you are less likely to lose data.

Netvyper · 10 May 2007 at 12:50

Im fairly sure that even in raid0 - the card will only allow you to use the same amount of space on the larger drives, as the capacity of the smallest one. so you'd essentially get 4x 74gb, and a whole bunch of wasted space.

You have several options; the best is probably just to connect the disks in JBOD, and then either use each disk for storing something different, or just stuff data on them.

You could use windows dynamic disks, which will allow you to create 1 large 'virtal' disk accross all 4 of your physical disks, but this isnt an ideal solution for data security, iirc if you loose 1 disk; you loose all the data.

The final way is with a linux based fileserver, this does the same thing as the windows dynamic disks, but in a much better way. I dont have the details to hand, but I remember reading several good things about linux storage setups, a little wiki & googling would probably help you out if your interested in this

Scott Salisbury · 11 May 2007 at 13:36

Ah right

Thanks for the replies guys. I have a few more things to think about now. Doesn't sound like it's worth the effort anymore.

Cheers

matja · 11 May 2007 at 14:27

If you used Linux md (software RAID) you could configure the disks as follows to maximise redundancy in case of drive failure and minimise overhead :

assuming -
sda = 300gb
sdb = 200gb
sdc = 74gb
sdd = 200gb

then -

sda1 = 200gb, sda2 = 74gb, sda3 = 26gb (unallocated)
sdb1 = 200gb
sdc1 = 74gb
sdd1 = 200gb

md0 = raid5 of sda1, sdb1, sdd1 (400gb)
md1 = raid1 of sda1, sdc1 (74gb)

md2 = jbod/linear of md0, md1 (474gb)

This would give you 474gb of contiguous storage allowing for any single drive failure and even some cases of two-drive failure (sdb/sdd + sdc), with 26gb of slack.

They can attached via any disk controller that Linux supports, the md mechanism doesn't care - even if you shutdown, swap all the disks onto new controllers, and boot again - this is the beauty of software RAID.