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List:       solid
Subject:    Re: multiple transaction logs/RAID
From:       borud () guardian ! no
Date:       1998-06-09 8:48:19
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[Brian Slesinsky]
| 
| > I don't understand the question.  a RAID is transparent to the
| > applications running on it.  what do you mean by "work well"?
| 
| My experience with RAID was that at a previous company I had my home
| directory on an NFS-mounted RAID system.  It could be quite slow at
| times. 

if you NFS-mount a volume all bets are off with respect to performance
unless you have a high-speed network and your NFS-server is a Network
Appliances server (which has been known to give very good
performance).

| Also, we lost a day's work and had to restore from tape because the
| RAID system had some kind of electrical problem that corrupted more
| than one disk.

well, that should definitively not happen, but I suspect that it
wouldn't be much different than if you had only one physical drive.

| Perhaps that was unusual, but as a result, I'm not willing to the
| reliability of *any* hardware for granted (which is why I would
| really prefer to have more than one transaction log and use separate
| SCSI controllers going to separate disks).

given that you have a functional and not a broken RAID system I can't
see why this should be any safer.

| But perhaps I will take a chance on a RAID.  So, I would like to
| know how using a RAID would affect Solid's performance, and since
| RAID systems tend to cache writes, I'd like be sure that when a
| transaction is committed, the transaction log is written all the way
| to disk.

you'll have to talk to your RAID vendor about that.  as far as I know,
most SCSI-drives don't cache writes unless instructed to do so.  your
RAID vendor should be able to tell you wether write cacheing is on or
off, or how you can configure it.

talk to your RAID vendor.

-Bjørn

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