Some questions about RAID

Hey everyone,

I'm running a PowerMac G5 as my server with Leopard Server. It has a 160GB SATA hard drive current with the OS installed on it. I'm looking to get a second drive and use RAID for better performance. I run a small business, with 3-4 users connecting to the server. It's my gateway and provides DHCP to users, with light file sharing, print server and is our mail server as well.

I want to do RAID either way. What I'm wondering is would I be better to do a striped type RAID to get better performance, or should I go the mirrored route for a sort of backup? Is the performance with striped raid much better? Just trying to figure out my best path.

My second question is my main hard drive is 160GB, but I don't want to buy a 2nd one that small. So if I get another that's 500gb, would I just make a 160GB partition for RAID and use the rest for something else, or do both drives need to be 160gb? Thanks!!

(I actually should add as well, this is a PowerMac G5 dual 2Ghz late 2005. I honestly don't know much about RAID or what's needed, I assumed since it's a PowerMac that I could just pop in another drive and set up some type of raid. So to help out anyone that answers, I'm looking to really just buy another drive and set something up, unless I absolutely have to buy more hardware to do raid. If that's the case I most likely won't do it . Thanks!)

For a server environment I'd highly recommend you run a RAID 1 array. RAID0 as you probably know has no redundancy.

Now if you consider 'uptime' for the server, say one drive fails on RAID0. You've lost everything, you need to go to the store and get another drive the same as the other one (or maybe you'll need to buy 2 new ones because they don't make the model you had anymore) and then you can restore from a backup and probably configure it again depending on the backup. That will take at least 2 days.

If you run RAID1 and a drive fails the sever won't act much different apart from a warning from the RAID controller. You then order a new drive, pop it in, fire the server back up and it begins mirroring the drives again. Total downtime - 30 mins tops!

The answer to your second question is, you will basically need to start again. Both drives must be identical you can't do a RAID array with a 160 + 500GiB drive. Simply by two new 500GiB drives and copy the contents from the old drive over with a USB2 hard drive caddy.

Just a note, please don't rely on RAID1 as your only backup. If your server gets a power surge or two drives fail etc, you'd have nothing. And always keep the current backup of the server off-site too.

As far as hardware goes, I'm not sure if you'll need a RAID controller card or if OS X can do some sort of software RAID - which isn't as good but it would be free!

If you need any explanation on the above let me know.

Cheers,

Marty

My two cents worth is not much different. I have Mirrored the OS drive in my W2000 server and RAID 5 the production files. I would never raid the OS with production - been there and cost me lots in $$$ and time. My RAID is built from 6x120 gb WD drives as that was the largest in 2000 and it is still running and I have swapped out a few (3 I believe) 120 WD drives into the RAID and it chugs on. Maybe overkill but the RAID card and the battery backup (on my 3rd battery backup) are critical to long term happiness.

Yes you should use a hardware card and do it right or expect to cry in your milk later. And YES you want it to be on a battery backup at the minimum.

Yeah RAID 5 would actually be ideal.

The server at my office runs 2x 72Gb SCSI SAS drives in RAID1 for OS (Win SBS 2003 Pro). Data is in a RAID 5 consisting of 4x 146Gb SCSI SAS drives.

However, the Dell server has 8 hot-swap drive bays - the G5 only has 2 drive bays. So you are severely limited, basically to RAID0 or 1. Unless you can find a unique way to mount more?!

In case you didn't know RAID 5 requires 3 or more drives (2 striped (like RAID0) and 1 for ECC).

TBH though, since you don't want to buy more hardware (RAID cards can be pricey) you'll be better off leaving it and sticking with a good backup plan!