Raid 1 reliable mirroring?

[dajo]

I have a dev machine which has critical data on it for my web site and my business (I have a separate rig for gaming and playing). I'm getting to the point where possible downtime in the event of a crash is starting to worry me.

I'm thinking of implementing a raid 1 solution using a SCSI card controller, not integrated controller.

Does anyone know if this is actually a safe way to do mirroring? I've read recently about some bad results for raid 1 on integrated solutions which is kind of scarey.

Assuming I have quality components installed, will a raid 1 SCSI solution work as expected, allowing for little downtime and avoiding having to reinstall everything?

Thanks!

 

[Peter]

If you're using a SCSI controller based RAID solution, with e.g. the LSI 20320R controller, then you'll be pretty safe and still as fast as you can expect from a SCSI solution. Host based, CPU software driven RAID? Bad move.

 

[Homerboy]

get a controller card and do RAID5
and RUN BACKUPS
RAID is not a viable backup solution. Get a tape drive or at the very least some sort of FTP backup that runs nightly to a diverse location.

 

[Zepper]

Why not an external Firewire drive for backups? Simple, inexpensive and just works. Then (depending on your OS) there is software that just sits there in the background copying changed files to your specified location - works with any storage unit with a drive letter.

Software RAID-1 should work just as well with SCSI as it does with IDE (PATA or SATA) - software is widely available to do mirroring with SCSI - no special controller needed. Win 2k/XP may have it already in it Storage Management functions. OTOH, RAID-1 is NOT a secure backup method. It should be viewed as primarily for limiting downtime. So you might want BOTH RAID-1 and a secure backup plan (using file-by-file backup software as drive image software is not a good backup method either) depending on your need for uptime.

For software RAID (0, 1, 1+0) to work at its best, you should also have ECC memory in your machine.

.bh.

 

[dajo]

It's not a valid backup method as far as, say, storing critical data off-site, but is it solid as far as allowing me to keep my rig up, and in allowing me to add a replacement second drive and be back in mirroring mode?

I will put in place a good back up method, but for now I want to avoid re-installing everything, and being down for any significant amount of time.

I appreciate your responses and your input.

 

[Peter]

Soft-mirroring doubles the amount of data that travel the PCI bus, and thus, on a mainboard with nothing but the usual miserable 33 MHz 32-bit slots, will choke the performance, quite so.

When the controller on the card does the mirroring, it won't. LSI 20320R, your entry point. I said that. 🙂

 

[Zepper]

Good mirroring software should wait in the background for a lull in the action (if possible) to write to the mirror - sort of like a big cache. You'd think SCSI-aware mirroring software would have the sense to set commands for the "live" drive to sync its data to the "mirror" drive by itself so the data wouldn't have to traverse the PCI bus a second time. SCSI is 'supposed' to be able to do that. Else why do we pay so much for it. Most users would not notice the difference. Now if the OP's dev machine is serving multiple users, then that might be a problem and the controller mentioned might be a worthwhile investment. Enquiring minds want to know...

.bh.

 

[Peter]

It already makes a difference with non-server situations. One single drive is saturating standard PCI already.

SCSI HDDs cannot typically act as transfer initiators. They're targets, requiring either the host SCSI controller or the host CPU to transfer the data to both drives.

 

[Zepper]

I found the adapter Peter mentioned at a good price if you decide to go for it.

.bh.