[THIN] Re: RAID 1
- From: "Dupris, Mike" <Mike.Dupris@xxxxxxxxxxxx>
- To: <thin@xxxxxxxxxxxxx>
- Date: Mon, 30 Apr 2007 16:29:38 -0500
Raid 1 out performs Raid 0 but is riskier because of the lack of
redundancy. Raid 1 is better best used for basic "stuff" that you can
easily get back on due to failure (NOS, easy applications quickly
installed) -think if you can rebuild it from disk (or blast down from an
image) then do a basic restore of a limited amount of settings or
configurations (from file) and your operation is back up and running
then RAID 1 is better for performance.
Raid 0 is delayed because of the read & compare then delete & writes.
Raid 1 spreads data across disks thereby spreading out the disk
operations across the array (relieving bottlenecks.)
Temporary files and system pagefiles can be kept on a single independent
disk (rather than the same disk -remember we are trying to limit the
times we have to wait on the arm to position the head on one of the
platters -for the matter, we are also wanting to remove overhead on an
array controller.) Risk: if that disk the temp/system file is located
on fails during production, that could cause a serious issue if your
system relies upon heavy pagefile use.
Transactions or archives should not be kept on Raid 1. RAID 1 should
not be used if the application's "presence" is not managed for you
(Clustered VIP, Farm) -I guess I am saying, if the box goes down and you
have another host that is going to handle the load then you shouldn't be
afraid to use RAID 1 over 0.
Here is a high performance production setup for Clustered or Farmed
boxes
[NOS] 3 disks, raid 1, controller A, disk cache enabled, PCI bus X (I
like at least 3 for dedicated OS ,volume -single patrician)
[TEMP] 1 disk, independent disk, disk cache enabled, controller B, PCI
bus Y
[DATA] Multiple disks, raid 5 or 10, disk write-through if Database,
controller C or SAN attached, PCI bus Z or SAN attached
Where XYZ are placeholders for whatever dedicated PCI buses are
available on your system.
Mike Dupris
From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On
Behalf Of Andrew Wood
Sent: Monday, April 30, 2007 7:45 AM
To: thin@xxxxxxxxxxxxx
Subject: [THIN] Re: RAID 1
I've always wanted to do this but never had the time - it'd be
interesting to note what the performance gain was in relation to the
fact that you increase your risk of causing an outage due to a single
disk failure...
From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On
Behalf Of Joe Shonk
Sent: 28 April 2007 15:38
To: thin@xxxxxxxxxxxxx
Subject: [THIN] Re: RAID 1
It's a very interesting question indeed. Which blades are you using?
What kind of i/o controller?
Putting the pagefile (alone) on a second partition will help performance
with regards that the pagefile will be create as one large
continuous(non fragmented) file.
With some controllers (those with NO cache), you can see an increase in
performance by not using RAID 1 and have two independent spindles and
put the pagefile, temp dirs, and spooler on the second drive. But if
you are going to do that, then why not set it up a RAID 0 with a second
partition for the pagefile. We literally 2x the performance in reads
and writes with the configuration over RAID 1.
Joe
On 4/27/07, Charles Watts <gregwatts77@xxxxxxxxxxx> wrote:
We are using HP Blades with RIAD 1 for our Citrix Servers on Windows
Server
2003 SP1. My question is would we get better disk i/o performance if we
partioned the RAID 1 into two partitions and stuck the page file, temp
directories and programs on the second partition? If not has any one
used a
RAMDISK for this? Or is their an argument for eliminating RAID 1
altogether
and just put the page file, temp directories on the second hard drive
(better performance and more disk space). Since I have a boat load of
blades
where is the risk? So I lose one or two drives a year on my servers and
each
time 50 - 60 users get kicked off. heck! I do that accidently at least
once
a year!? Managment might not buy that argument but If the performance
gain
is significant then it's worth it. Your thoughts?
Thanks,
Greg
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