Am Mittwoch, 9. Mai 2007 schrieb Alfred von Campe:
> The recent thread on Anaconda and RAID10 made me start to think about
> how to partition a server I'm about to set up. I have two 146GB SCSI
> drives on an IBM x3550. It will be used as a build system. As such,
> there is no critical data on these systems, as the source code will
> be checked out of our source control system, and the build results
> are copied to another system. I usually build my systems with
> Kickstart, so if a disk dies, I can rebuild it quickly.
>
> Given all that, how would you partition these disks? I keep going
> back and forth between various options (HW RAID, SW RAID, LVM,
> etc.). I guess speed is more important to me than redundancy. I'm
> tempted to install the OS on one drive and use the entire second
> drive for data. This way I can rebuild or upgrade the OS without
> touching the data. But that will waste a lot of disk space, as the
> OS does not need 146GB.
>
> The only thing I'm pretty sure of is to put 2GB of swap on each
> drive, but after that everything is still in the air. I am looking
> for any and all suggestions from the collective wisdom and experience
> of this list.
Ask yourself this question: Does the company loose money when the build system
is down for restore? How much? How long does a restore take?
Mirroring disks is not a replacement for backup. It is a way to improve
availability of a system (no downtime when a disc dies), so it might even be
interesting when there is no important data on the machine. If this is
important for you use RAID-1 for the entire discs.
If decreased availability is not a problem for you (you can easily afford a
day of downtime when a disc dies) use RAID-0 for the entire discs. It will
give you a nice performance boost. Especially on a build host people will
love the extra performance of the disc array.
A combination of RAID-0 and RAID-1 may also be an option: Make a small RAID-1
partition for the operating system (say 20GB) and a big RAID-0 partition for
the data. This way you will get maximum performance on the data partition,
but when a disc dies you do not need to reinstall the operating system. Just
put in a new disc, let the RAID-1 rebuild itself in the background and
restore your data. This can reduce the downtime (and the amount of work for
you) when a disc dies considerably.
HW vs SW RAID: Kind of a religious question. HW has some advantages when using
RAID-5 or RAID-6 (less CPU load). When using RAID-0 or RAID-1 there should
not be any difference performance wise. HW RAID gives you some advantages in
terms of handling, i.e. hotplugging of discs, nice administration console,
RAID-10 during install ;-), etc. It's up to you to decide whether it is worth
the money. Plus you need to find a controller that is well supported in
Linux.
regards,
Andreas Micklei
P.s. Putting lots of RAM into the machine (for the buffer cache) has more
impact than RAID-0 in my experience. Of course that depends on your
filesystem usage pattern.
P.p.s. Creating one swap partition on each disc is correct, because swapping
to RAID-0 is useless. Only if you decide to use RAID-1 for the whole disc you
should also swap to RAID-1.
--
Andreas Micklei
IVISTAR Kommunikationssysteme AG
Ehrenbergstr. 19 / 10245 Berlin, Germany
http://www.ivistar.de
Handelsregister: Berlin Charlottenburg HRB 75173
Umsatzsteuer-ID: DE207795030
Vorstand: Dr.-Ing. Dirk Elias
Aufsichtsratsvorsitz: Dipl.-Betriebsw. Frank Bindel
_______________________________________________
CentOS mailing list
CentOS@xxxxxxxxxx
http://lists.centos.org/mailman/listinfo/centos
