Raid. Need some Answers Please

  User-312386 19:09 07 May 2006

Hi all

I now have 4 Hard Discs

1 74GB Raptor 10,000rpm
2 300GB 7,200 RPM
3 160GB 7,200 RPM
4 120GB 7,200 RPM

What i want to know is can i put the 300gb, the 160GB and 120 GB in a RAID config? Or do you need the same size drives for a RAID config?

I don't know anything about RAID so any input will be useful.

I wan to keep the 74GB one as the main drive as it is good for gaming.

Many thanks in advance

  Fruit Bat /\0/\ 19:13 07 May 2006
  Totally-braindead 19:19 07 May 2006

I am given to understand the drives have to be the same. I have RAID and bought 2 drives the same for this purpose. I don't know if it is possible to have RAID on two drives with different capacities it may well be possible but if it is possible you would lose some of the capacity from one of the drives as they have to be the same. So if you connected the 120 gig and the 160 gig in a RAID configuration you would, supposing it did work, lose at least 40 gigs.

If you really do want to try it I would buy another drive exactly the same as one you already have and take the surplus drive out, stick it in an enclosure and use it as an external hard drive presumming you don't have one already.

  User-312386 19:21 07 May 2006

If i did Raid0 surely they would be spread across and then you would have all 580GB in one "Logical drive"

I am only guessing as i just read Fruit Bat /\0/\'s peice he just gave me

  Totally-braindead 19:37 07 May 2006

From my manual RAID 0 striping, 2 drives must be the same, RAID 1 mirroring 2 drives, does say if you're using a new drive with an existing one it must be either the same size or larger but I would think you would lose the extra space. RAID 0+1 striping and mirroring, needs 4 drives, RAID 5 needs minimum 3 identical hard drives, RAID 10 needs a minimum of 4 hard drives.

  Totally-braindead 19:43 07 May 2006

If you did RAID 0 I would think, if it worked and I'm not sure if it would as my manual definately states that for this they must be the same capacity, that you would end up with 2 drives the size of your lowest capacity one. Raid 0 as far as I know does not allow you to use 3 drives, according to my manual.
Actually read my manual Page 5.21 click here

  UncleP 00:09 08 May 2006

Yes, I think that for most common RAID configurations the disk size has to be the same. This doesn't mean that you can't use disks with different capacities, just that they will be trimmed down to that of the smaller or smallest. This is obvious with RAID 1, as each disk has a mirror copy of the data. With RAID 0 types, the data stream is split into equally-sized chunks or 'stripes', and sent sequentially to the component disks. Once the smallest disk is full, the process has to stop as you either lose part of the data stream, or lose track of where the 'stripes' are being stored.

There was a similar discussion in a recent thread

click here

The reference given in my contribution is worth looking at; it's quite detailed but very clearly written and easy to understand.

  UncleP 00:20 08 May 2006

the reference is in my second contribution and goes direct to the section on RAID 5 arrays. To start at the beginning try

click here

  User-312386 18:43 08 May 2006

thanks guys for all your help

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