RAID5 -- Does it matter what HDDs are used?

[Cerulean]

I have a RAID5 (four harddrives, right?), and one of the four are dead. Does it matter what kind of brand or model of HDD I would buy to replace it? And is all I have to do is slide in the new drive into the dead drives hotswap slot?

 

[Red Squirrel]

I prefer using the same manufacturer/model, but no it does not really matter. Keep in mind though if one drive performs less good, it will slow down the whole array. So if you do get another drive try to get a higher performance one so it does not slow down the array.

Edit: Forgot to mention, I'm talking about software raid. With hardware raid think it really depends on the card.

 

[YeOldeStonecat]

Usually you can mix-match. Any faster drives will slow down to run compatible..yes in hardware too, and larger capacities....will just be ignored, only the matching capacity will be used.

Ideally you want matching make/models for compatibility and optimal performance.

 

[doh]

You probably want to use disks that are rated for use in a RAID environment. Match other specs if you can. A larger disk is fine but you won't get the extra space, a slower disk will impact performance.

 

[Cerulean]

So I could replace all four drives if I just do one drive at a time... perhaps it would be smarter to just replace three with 15k 80GB SCSI's and then a lower performance drive so as to extend the lifetime of the 15k drives.

Do SW/HW RAID controllers automatically rebuild/extend the RAID when replacing a dead drive of an RAID5 array? No user interaction required?

 

[Red Squirrel]

Depends on the controller. I only use Linux MD software raid at home and I have to run a 1 line command to tell it to rebuild. Basically I just tell it to insert the drive into the array, and it gets to work and I can view the status.

 

[Hallis]

+1 to pretty much what everybody else has said. When I put together my RAID5 i bought 2 extra drives of the same make/model to have as spares just in case. But it shouldn't be required. Raid5 is generally used for drive fail tolerance and not performance.

 

[YeOldeStonecat]

Do SW/HW RAID controllers automatically rebuild/extend the RAID when replacing a dead drive of an RAID5 array? No user interaction required?

What is your RAID controller? Most hardware RAID controllers are automatic on the rebuild. Some have software that runs in Windows so you can monitor that. Others you have to bounce the rig and jump into some BIOS like config utility during bootup.