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James Harvard
04-19-2001, 06:46 PM
Background: I have a colocated web / database server which is soon to be running a site that includes auction features. The stuff that is on it currently is either copied to the server from my desktop or changes infrequently enough to be OK backed up occasionally down to my desktop over the net. However, with this auction site the loss of even a few hours data is not a situation I ever wish to face.

My thinking so far: For real time data security it seems that I need RAID 1. Performance is not a major concern for me - the server is a Sawtooth G4 400MHz and it seems to potter along very nicely with its standard IDE HD. So, why not save my pounds (I'm in England) and get the VST IDE RAID card and a couple of 20GB IDE disks - it's nearly 1/2 the investment required for a LVD SCSI setup. After all, I'm not looking for gangster I/O rates and even if one of the drives is more likely to fail sooner than a SCSI one... ... well drive failure is why I want RAID 1 in the first place.

[While I've been using Macs for a long time, I've never taken much interest in the ins & outs of storage. All the tedious 'my thought process' stuff above is there in the hope that someone will tap me on the shoulder if I'm marching off in completely the wrong direction on this. BTW, I hope I am in the right place for this - or should I be across the road in the IDE forum?]

Questions I hope someone can answer:

1) SoftRAID's web site says (to paraphrase) 'We Don't Do IDE', yet VST's PCI IDE controller comes with SoftRAID. Huh?

2) There a quite a comments on this site & in these forums to the effect that IDE is not a good basis for a RAID. But there seems to be an emphasis on speedy RAID 0 setups - is it just high performance RAID 0 that is the problem or could RAID 1 with IDE produce stability problems?

3) What actually happens if 1 drive in a RAID 1 setup fails? Does it just carry on using the remaining drive? Can stuff happen to RAIDs that needs human intervention before the volume is available again, or would interfere with the server's ability to recover itself from a crash? (For example, with FileMaker on a server if a database is damaged FileMaker throws up a dialogue, then refuses to do another thing until the dialogue is cleared - can similar things happen with software RAID?)

Big TIA,

James Harvard

Louie
04-20-2001, 02:06 PM
James:

I'm strictly a SCSI RAID person but there is one point of your question that I can address. When using an IDE controller card, it emulates SCSI. The Mac sees the drives as SCSI and, thus, SoftRAID can be used.

Someone else will need to comment on the other aspects of your question.

magician
04-21-2001, 12:30 AM
right.

the VST card emulates a SCSI host, fooling SoftRAID into handling the IDE drives.

the quick, simple answer to your question is, yes, you can use an UltraTek and a pair of IDE drives striped with SoftRAID in a RAID 1.

the longer answer is, if you are looking for security and data integrity, why compromise?

look at the warranties on IDE drives. Now look at the warranties on LVD SCSI drives. Interesting, huh?

I see no reason not to boot off the standard IDE drive.

for critical files, I would leave those on a RAID 1 volume. If one drive fails, you get a notice, and the other drive continues serving files. You can shut-down, pull the bad drive, install a replacement, fire up the machine, initialize the new drive, then tell the RAID 1 volume to use it, and then put the server back online. The server will dish files off the remaining drive while it rebuilds its mirror on the secondary drive in the background. Your down-time, while you swap drives, can easily be less than five minutes.

I've never run a mission-critical service using IDE hardware. I wouldn't do it, personally. Yes, I am a SCSI fascist. I got this way thru environmental influences: it is not a genetic condition. I wasn't born this way.

I have done it using Cheetahs and ATTO boards with SoftRAID. You just set it up, configure your server conservatively, stress-test the hell out of it, and then you throw it to the wolves. Generally, it works fine. You can just move on to other stuff, and pull maintenance about once a week.

hope this helps.

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