RAID Gurus

[Amputate Your Head]

Anyone using a RAID mirroring system mainboard that can tell me performance/benefits type stuff of using RAID versus manual disk imaging or simply burning everything to CDs...? Is using both methods together even better or just a waste of time?

I've got quite a bit of gear here that I'm contemplating reconfiguring, but not sure which way I wanna go with it yet... so any practical experiences using a RAID system would be greatly appreciated.

Thanks

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Just another monkey with a computer.

[DarkJedi]

indeed

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[Amputate Your Head]

Also, (should've included this before...) if I set up a RAID mirror on a board with four controllers, (2 RAID controllers and two non-RAID left open), can the unused non-RAID controllers still be used for hot-swap hard disks, or does something like that confuse and complicate the boot processes?

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Just another monkey with a computer.

[Phil21]

Er.. RAID is not meant to be an alternative for regular backups. It's meant to provide some data redundancy for hardware failure, availability, and speed.

A pair (or more) drives in RAID 1 with a decent controller (hardware based, no IDE RAID cards save perhaps the higher-end 3ware cards are actually hardware based, they rely heavily on CPU), shouldn't give you a noticeable decrease in speed. What usually happens is that write speed will decrease marginally (due to having to align two heads), and read speed will pick up a little bit (due to the ability of some controllers to read data bit A off drive A, and bit B off drive B, at the same time).

As for your second question you need to be more clear. A normal SCSI or IDE controller will not support hotswap, in fact it's fairly dangerous to hotswap IDE devices when the controller was not designed for it. Most controllers that allow IDE hotswap actually physically turn off the BUS for that drive before you can physically remove it. If your asking if you can have a single disk as a normal drive, sure. But they can't be used as hotspares or anything on the RAID volume.

Some RAID cards support using multiple RAID cards in a failover configuration so if the host adaptor fails it will switch over to the other one. Some even support a logical RAID volume spread across two controllers, so you can have more devices in one array.. Keep in mind that decreases your theoretical reliability by a factor of the number of cards you have.

I dunno, be a lot more specific in your question. :P

-Phil

[Amputate Your Head]

Okay... no RAID cards here. Controllers are built into the board. ( It's a nice board )... Non-RAID controllers are ATA100. So basically, right now, I'm using the non-RAID controllers for Primary (with a slave attached) and Secondary to the burner. What I'd like to do is set up a RAID mirror using the built in controllers, put the burner on the ATA100 Primary, and then hook up a removeable HD rack on the Secondary ATA100. (shouldn't have said hot-swap....bad use of lingo there on my part) Not hot-swap, but removeable between boots. I can't really foresee any problems with using that layout, but.... that's why I'm asking. Whatta ya think?

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Just another monkey with a computer.

[Phil21]

Should work fine.

They are still RAID cards (well, as much as a promise/fastrak is anyways), even though are are on the board. The chips are just on the mainboard instead of in a PCI slot.. They still use the same PCI bus to communicate, and the mobo "sees" a normal "card" in the system.

But yeah, don't see anything wrong w/ that setup at all.

-Phil

[Amputate Your Head]

Why should RAID not be used as a data backup? I realize it's designed for hardware failure type scenarios, but isn't that what a backup is for? One disk fails, drop in a new one, and rebuild a new array....? Or am I missing a bigger picture...?

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Just another monkey with a computer.

[Amputate Your Head]

thanks for the info Phil.....

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Just another monkey with a computer.

[Phil21]

See why a fairly popular freehost went down here as to why.

File system corruption. Configuration errors happen far more than most hardware failures, and are the primary cause for downtime.

I.e. if your controller card decides to flip out one day, your array is pretty screwed. Also keep in mind your disks are not portable between one brand controller to another, they use different means of striping and such.

For personal use though, I think it's fine for most things. Save that keycode for your $1M in the swiss bank account. It's just I see a lot of hosts thing that because they have RAID set up, that they are covered for backups. No so. :P

-Phil

[Theo]

It sounds as an expensive solution if you want it for personal use.

[Amputate Your Head]

Yeah, I see what you mean... I'm just sick and tired of waiting for stuff to burn to CDs... it gets to be a lengthy process when you're trying to burn 40 gigs worth of data... so I think I'll set up the RAID disks, and use the removeables HDDs for primary data storage backup, and to hell with the CDRWs... sounds like a good plan for most any situation. Just wanted to lay it all out and see what was what...

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Just another monkey with a computer.

[Dopy]

Phil21 sums up the basics

It might help if you read this raid document, people get confused as to what raid is really for.
http://www.ahinc.com/raid.htm

If anyone needs help with ATI or Suzic raid set-ups I have good knowlege of these from our Dell Power Edge office servers.

[Amputate Your Head]

Looks good Dopy.... I like articles that are clear and to the point. But it only reinforces my decision... RAID it will be with removeable HDDs for data backup and extra storage. (I will be using RAID 1) Now if I can just figure out a way to do all of this in a five minute time span so the whole damn works isn't offline all day while I switch mainboards...

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Just another monkey with a computer.

[Dopy]

If you have the hardware already, then why not, you will be giving yourself a reliable real time back up system by using raid 1 mirror drive. As for setting up in 5 mins, only ever happened to me once

[Amputate Your Head]

yeah, I already got the gear... but it's spread out through a few different boxes here, with the main box serving up sites. It's kind of a long way around, but I'm thinkin' if I duplicate the server main drive, slap it in another machine and plug it in, I'd be down for all of about five minutes when switching boxes to the router.... then I could take down the other boxes, and switch out mainboards at my leisure.... my god, sometimes I amaze even myself...

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Just another monkey with a computer.

[Phil21]

heheh. swap the drive into another box you have laying around and boot up. There, you have your sites up.

Then use a network transfer to x-fer the files to the new box once you get the array setup and such.

It's how we upgrade servers here, about 15 total minutes downtime in theory.

-Phil

[Amputate Your Head]

Hey Phil, do you guys ever use any FireWire stuff? Wondering if it's something I should spend money on... or if it's still in the novelty stages.

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Just another monkey with a computer.

[magnatique]

for raid purposes, it has to be two indentical drives, right?

[Amputate Your Head]

Originally posted by magnatique:
for raid purposes, it has to be two indentical drives, right?

Depends on the RAID level. If you're striping, then yes... but if you're RAID 1 mirroring, using an existing data drive... then no...

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Just another monkey with a computer.

[This message has been edited by Amputate Your Head (edited 10-14-2001).]

[magnatique]

cool, thanks