RE: [ActiveDir] Raid suggestions for DC maybe OT

[joe]

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] -- Posting is provided "AS IS", and confers no rights or warranties ...       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