On Tue, 6 Apr 1999, Stein Gjoen wrote:
Hi,
> In the Multi Disk HOWTO there are already some notes on
> optimum use of disks and RAID levels that you might find
> of interest.
> http://www.nyx.net/~sgjoen/disk.html
>
> All feedback is welcome; I wrote it.
I have a little suggestion regarding the use of raid that involves
IDE. I know you already know that, but i think it can be said clearlier:
1.- If you do IDE raid, use both ports (eg, raid0 or raid1 on
hda1 and hdc1). Reason follows.
This is obvious. What maybe isn't obvious, because is somewhat a
odd setup, is a 0+1 IDE raid. Surelly it won't win any raid award of the
year, but maybe somebody will aim those targets:
1 - minimum cost
2 - maximum storage
3 - redundancy
4 - the best possible performance
It's a high -readily available (no tapes) cheap mass storage
solution that suits some requirements, e.g. a Intranet repository.
Also, an SMP machine will behave (as mine) surprisingly well.
Having a 0+1 IDE raid of 20Gb cost less than $530. I'd use scsi
for the system disc, however. But SCSI II is also cheap nowadays.
One could wonder (as I posted sometime ago) how to setup the 0
raids. Do i make raids 0 on the master/slave device of the same IDE port,
and mirror both "ports" later? or do i do raids 0 on master/master
slave/slave devices and later mirror them?
The answer is keep raids 0 on the same controller, i.e. raid0 A
hdaX-hdbX, raid0 B hdcX-hddX and later mirror them.
The reason is that on a master-slave setup, the slave disc is controlled
by the master. If on a [hda-hdc]+[hdb-hdd] raid 0+1 the master device of
*any* IDE controller fails, the slave will inmediatly fail also (I'd bet
it surelly will happen if it's the slave who fails, so this statement
could be widened to "if *any* disc fails"), rendering your raid 0+1
inmediatly unusable, and making recovery thougher.
Just my 2 cents.
*****---(*)---**********************************************---------->
Francisco J. Montilla Systems & Network administrator
[EMAIL PROTECTED] irc: pukka Seville Spain
INSFLUG (LiNUX) Coordinator. www.insflug.org - ftp.insflug.org
