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Jonathan -
275 replication links seems, at least to my tired eyes this
AM, to be a lot. Are you running a branch office environment, or is this a
number of remote sites that link back to a single hub?
I'm interested as to why there are so many repl links to
your DCs, only if it's one DC. In my experience, that's not optimal, and
we can provide some prescriptive guidance to help optimize the topology with no
addition of hardware, just some tuning of site/subnet
configurations.
Rick [msft]
-- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Carr, Jonathan (OFT) Sent: Tuesday, November 08, 2005 6:00 AM To: ActiveDir@mail.activedir.org Subject: RE: [ActiveDir] Raid suggestions for DC maybe OT I don't know about you but rebuilding DC's is not fun
stuff. Especially if it has 275 replication links to it from remote
DC's.. believe me spend the money on the fault
tolerance.. From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of joe Sent: Monday, November 07, 2005 10:09 PM To: ActiveDir@mail.activedir.org Subject: RE: [ActiveDir] Raid suggestions for DC maybe OT How about just not partitioning the whole disk of the
larger disks? Note I didn't come up with that idea, that came from a young
whippersnapper I know out of Redmond whom I was discussing the fastest AD disk
configs with a few weeks ago. I haven't tried it but it makes sense to me. Just
allocate maybe 10-12GB of each of the 36GB drives across an array or
so.
Course you could always say screw the fault tolerant RAIDs,
this isn't Exchange, and run commando with a stripe set. If you have enough
extra DC capacity in the site you could have them all running really fast and
then when one blows it just goes away. Most applications that are written
properly for AD handle that just fine except apps that hard sync to a single DC.
If I have 7-8 disks, I wouldn't hesitate to put them in a
single RAID-10/0+1 type config. OS and Logs are snoring on most DCs. All of the
action is around the DIT unless you get that baby into memory which was the
first I think 20 responses I got from the whippersnapper. Use 64 bit. I know
but... use 64 bit... I know but.... use 64 bit.... I know but.... are you still
here, use 64 bit....
joe From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Carr, Jonathan (OFT) Sent: Monday, November 07, 2005 6:54 AM To: ActiveDir@mail.activedir.org Subject: RE: [ActiveDir] Raid suggestions for DC maybe OT
We have allot of users coming back to our central site and
we use the following config.
adapter #1 ====> raid 1 ( 2 disk)
O/S
adapter #2 ====>raid 1 ( 2 disk) AD
LOGS
adapter #3 ===> raid 5 (3 disk) with
global hot spare AD Data
the key to this using this is that all the equipment (SCSI
disk,SCSI controller) is Ultra 320 spec with low latency and low seek
times (15 K rpm usually). The other thing that has been
noticed is that use as small a disk as you can get. (8 GB)
Some of the manufacturers are saying they only can supply 36GB drives on new
equipment. These drive are ok but the seek time goes up because of
the size of the drive
this config works good also
adapter #1 ====> raid 1 ( 2 disk)
O/S
adapter #2 ====>raid 1 ( 2 disk) AD
LOGS and raid 5 (3 disk) with global hot
spare (total of 6 on this channel)
hope this
helps
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LOL. I actually pinged Rick on the "official" guidelines
previously for an Enterprise class DC with 4 disks, he was actually one of 4
people I queried since I hadn't seen what I considered good official docs on it.
Rick quoted the K3 Deployment guide which is definitely a good start. It
indicates
RAID 1 - OS
RAID 1 - Logs
RAID 1 or 0+1 - SYSVOL/DIT
If you have less than 1000 users using the DC it says you
can use one single RAID-1 for the whole thing. Though you have the same issue
here as you have for anything, how are the 1000 users using it and what else is
using it? Exchange? If so, I doubt I would do a single RAID-1 unless it was very
few users.
Otherwise you are looking at a minimum of 6 disks for all
RAID-1s or 8 disks if 0+1 and RAID-1.
When you actually look at it, the OS and the logs are using
little IOPS on a dedicated DC and splitting them off onto their own "disk" is
probably unneccessary. The DIT assuming it isn't all cached and is being heavily
hit (like say by Exchange) is raping the disk subsystem. When you have an app
that wants lots of IOPS what do you? You increase the number of spindles... So
for throughput, the fastest four disk configuration is going to
be a RAID-5 or a 0+1 or 10. In tests I did several years ago with one
hardware vendor RAID-10 and 5 were very close (within a few IOPS) with
RAID-5 eeking out the lead. They both blew RAID-1 away. In more recent tests I
heard of from someone using another hardware vendor, RAID 0+1 eeked out over
RAID-5 by a few IOPS and again blew RAID-1 out of the water. Obviously the
tests were different so I recommend folks do their own testing with their own
hardware. The fastest disk configs I am aware of are 6 and 8 disk RAID-10/0+1
setups with 8 disks supposedly being rock star fast if you have the room
internally. To put it another way, if I had 8 disks, I certainly wouldn't be
following the deployment guide config for those disks, it would be a RAID-10/0+1
setup. The 6 disk RAID-10s (The Dells I was using then didn't support 0+1) I
built about 3 or 4 years ago were screaming fast compared to everything else at
the time I had worked with. Now I don't do anything with hardware, I am more
cerebral. ;o)
And note, obviously I am not talking software RAID, this is
all hardware. Software RAID isn't something you use for production machines IMO.
joe
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Rick Kingslan Sent: Sunday, November 06, 2005 10:17 AM To: ActiveDir@mail.activedir.org Subject: RE: [ActiveDir] Raid suggestions for DC maybe OT Dan - there will likely be as many opinions on this topic
on this list as there are knots on joe's head.
Basic rules for a DC are this (IMHO):
Mirrored (or RAID1) for OS
Mirrored (or RAID1) for DIT and Logs
You can certainly host a third mirrored pair for the logs,
but that will mostly depend upon how BUSY your AD is and how high the
replication traffic, changes, updates etc. that you
experience.
If you're asking this, you most likely have a newer AD, or
are re-architecting. In either case, I'd start with the above and then
monitor the performance with PerfMon. Make some decisions on whether to
ADD the third mirror based upon the I/O and performance impact of log writes vs.
impact on the database reads/writes.
Hope this helps!
Rick [msft]
-- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dan Cox Sent: Sunday, November 06, 2005 1:31 AM To: ActiveDir@mail.activedir.org Subject: [ActiveDir] Raid suggestions for DC maybe OT What would be the suggested RAID and partitioning
scheme for a Domain controller.
Any suggestions are appreciated.
Thanks. Dan Cox
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- RE: [ActiveDir] Raid suggestions for DC maybe OT Rick Kingslan
- RE: [ActiveDir] Raid suggestions for DC maybe ... Ed Crowley [MVP]
- Re: [ActiveDir] Raid suggestions for DC maybe ... Phil Renouf
- RE: [ActiveDir] Raid suggestions for DC maybe ... Carr, Jonathan \(OFT\)
