Below are the comments I got - thank all of you for taking the time to
answer and give suggestions. The LSM Installation guide and AdvFS
Administration book are both good resources, along with the guidence below I
feel like I can make a good choice.
Thanks for your help.
Sally
*************************************************Tru64 Unix
[tru64_at_myway.worldonline.co.uk]
If you ask 10 people...you will probably get 10 different answers...but a
common theme that should run amongst them :
keep your OS on a separate mirrored disk of its own...don't mix user/app
data with your OS
If you can - get him to separate /tmp and /var/tmp away from the root
partition aswell.
2nd volume - depends on the application and I guess....how much space you
need against how much resilience you need against how much performance you
need.
I have to say though - I don't know what your 'Compaq' guy is talking
about - 'download something to implement raid 0-3 via software....' it is
enabled at kernel level...but there is nothing to download that I know of!!
LSM as far as I know, although separately licensed comes as part of the
OS...you just have to enable it...eg..make sure the right subsets are in
use...most of it (although perhaps not the GUI management frontends and man
pages) is installed by default and in fact I think it has to be...there is
no option to not install those BASE bits...check your subsets for this by
typing #setld -i | more and read through..you should see some installed LSM
BASE subsets.
I think I'd still rather have a stripe (performance) or raid (resilience)
set on my single controller..than a mirror for my application..for
deffo...be it software or raid...your apps performance will take a right hit
as a mirror!!
There is no reason you cannot have a small mirror for Unidata and a raidset
for the app...
**************************************************Juan Carlos Cruz R.
[jccruz_at_cmaresa.com]
RAID Hardware no affect the OS.
Usually by harware is create RAID0 , example 3 disk of 9.1 GB in RAID0
with channel 1, and with LSM is create Mirrors, Example , 3 discos of 9.1 GB
in RAID0 with channel 2 and with Logical Storage Manager create Mirrors of
this two new units,
************************************************Hines, Bruce D
[bruce.hines_at_eds.com]
http://www.raid-advisory.com/
This should help with understanding the RAID terminology.
LSM is the RAID software? unless you have purchased 3rd party something
else.
LSM can be configured to run RAID-0 (stripe), RAID-1 (mirror), RAID-10
(mirror/stripe) and RAID-5 (parity). Remember, host base RAID does have
overhead associated with it. Typically, RAID is pushed out to the
controllers. You need to ask questions, are we protecting data? are we
interested in performance? what about SPOF (single-point-of-failure)?
This should determine how and what you need to configure within LSM.
Typical installation use LSM to mirror their system volumes across multiple
SCSI buses, this give them protection and eliminates SPOF. It only has
minimal overhead for the dual writes and better read performance when it can
read from either volume in the mirror set.
Since you will only have a single SCSI bus with 6 disks:
- don't stripe, you would have no performance gains at the cost of
more overhead to CPU (striping to useful when you have multiple
SCSI buses and the I/O load gets spread across, better perform)
- RAID-5 would give you more disk capacity but at a cost, it will
be slower, good use when you have a controller based and want to
get better $ per GB
- mirrors, for protection of data, no performance gains
***************************************************Fletcher, Joe
[joe.fletcher_at_Metapack.com]
In this case I think LSM is the RAID software. What will happen is that the
o/s will go in on one volume and the remaining disks will be formed on LSM
mirrored stripesets. Generally works fine. However you only have a single
controller so theres one SPOF. Also, say you create root volume group on two
of the 18Gb drives as a mirror pair.
You are then left with 4 drives. To use any kind of mirroring you will end
up with a total of 36Gb usable sapce.
You might want to look at root vol on one mirror pair then create a RAID5
set out of the other 4 to maximise your storage. ADVFS simply becomes the
on-disk structure when the volumes are formatted.
*******************************ORIGINAL
QUESTION***************************************
Managers,
This is my first experience in setting up a unix system. I am being
confronted with RAID from several different directions and would like some
advice/information. We did not purchase RAID hardware. We have 6 18 GB
harddrives with one KZPBA-CA controller. The engineer who is going to
install the OS is talking about installing RAID software to configure the
disks. We have purchased the licenses for LSM, I have researched and come
up with a proposal for LSM disk groups and volumes along with the AdvFS
configuration that will suit our needs (mirrored/mirrored striped).
Question: The RAID software configuration within the kernel (what the
engineer is wanting to install) - how will it affect being about to use LSM
at the OS level? Any clarification of RAID terminology would also be
appreciated.
Thank you.
_________________________________
Sally Weldon
Programmer/Analyst
Austin College
Sherman, Texas 75090
903.831.2053
Received on Tue Dec 04 2001 - 17:32:59 NZDT