[NMLUG] More RAID Questions

[chakara at kissmygrits.net (Kyle Petree)]

1) If performance is the issue - go hardware.  I've never done software
on high demand systems, but I do know that in software raid, in the
event of an OS crash takes hours to resync the data and during that time
drive performance is abysmal, bringing most systems to their knee's
until it is done.

2) I would think so.  IDE is a shared bus and you do feel it if moving
large amounts of data to/from 2 devices on the same cable.

3) In raid 5 one disk is given up to parity.  So if you have 3 40G
drives you have 80G storage.  If you have 5 40G drives in Raid 5 you
have 160G storage.

4) I'm not a fan of hard drive backups, but I'd do at least 2 external
(read USB/Firewire) drives for the backups, and physically unplug
one/plug the other each day.  Give you redundancy in case of a big
disaster...not to mention you can take one offsite.  I think with the
Promise raid you have to have all drives in an array on the same
controller card (a limitation that doesn't exist is software raid).  So,
it depends on how many IDE controllers are on the Promise card you get.
It would be best to put only one drive on each controller (read IDE
connector).  Hang your CD drive(s) off the onboard controllers.

5) I'm no real help here.  Hell, I'm probably not real help at all...



-----Original Message-----
From: nmlug-bounces@nmlug.org [mailto:nmlug-bounces@nmlug.org] On Behalf
Of Tim Emerick
Sent: Wednesday, February 23, 2005 2:26 PM
To: nmlug nmlug; nmglug@nmglug.org
Subject: [NMLUG] More RAID Questions

After considering all of the kind replies I received in response to my
last
RAID post I have a couple more questions that didn't seem to be clearly
addressed in any of the links that were sent.  Looks like I'll be nixing
the
simple RAID0 or RAID1 controller that is on my motherboard in favor of a
RAID5 scenario.

1. Someone noted that software raid was just as fast as hardware raid.
This
machine will be a mostly dedicated Samba Server on a P4 1.8ghz machine.
Does
this still hold true or should I get a dedicated Promise Controller that
supports RAID5?

2. I thought I read somewhere that you should only use Drive0 on each
controller when using with RAID or you will get horrible performance.
Does
that hold water?  My onboard Promise RAID controller can be configured
for
RAID or normal ATA100 IDE controllers.  As normal IDE controllers that
would 
give me 4 controllers with 2 drives each.  With the above limitation it
sounds like I would only be able to use the Drive0 on each controller
for my
raid array.  Could I use Drive1 for occasionally used devices
(IDE-DVD/CDrom,
Large Backup HD) without a performance hit?

3. What is the math for RAID5?  I really only need around 60 gigs of
storage.


4. I'm looking at getting 3 40 gig ATA100 HD's for the raid array to add
to
the existing small HD for the linux OS, a 200 GIG HD for a rolling
couple
days backup, and the IDE-CDrom drive.  How would you suggest hooking all
that
up considering question #2?

5. Any tuning tips for Samba with WinXP workstations?

Thanks in advance

Tim Emerick




		
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