What were the support reasons? Someone whined until they got the OS on RAID-1 because that is the way "everyone" says they should do it or another popular one is that is the way we "always" do it?
One of the issues is that most of the machines folks like to make into DCs just don't have enough disk slots to have multiple spindles for the DIT if you take up 4 for the OS and Logs. If you can get away with mirror/mirror/6 disk 0+1/10... Excellent, especially if x64 with sufficient RAM. If the disk counters start to show queuing on the DIT drive greater than what I consider heavy load (~2x#spindles) though I wouldn't hesistate to tear that down and make it into a single 10 disk RAID 0+1/10/5. With x64, as Paul indicated, that generally shouldn't happen though unless you don't have enough memory or possibly you have recently rebooted and are defrosting the cache. Mostly though, people should be looking at their own perf counters and figuring out what they should be doing. Pay especially close attention to Exchange GCs during the "morning rush" and the after lunch "rush", those are the two areas that tend to initially start showing pain. joe -- O'Reilly Active Directory Third Edition - http://www.joeware.net/win/ad3e.htm -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Paul Williams Sent: Tuesday, October 17, 2006 5:03 AM To: ActiveDir@mail.activedir.org Subject: Re: [ActiveDir] Seperating Database and logs on seperate disks Having discussed this quite a lot recently, I'll give you all an insight into how I wanted to do it and how we are doing it (support reasons caused me to be overridden): [want] 6 disks in a RAID10 array, with three volumes: OS, DIT & Logs, SYSVOL and Scratch area. [reallity] 2 disks in a RAID1 array for OS; 4 disks in a RAID10 array for DIT & Logs, with another volume for SYSVOL and scratch. Scratch contains the IFM directory (temporarily) and perf logs, etc. I agree with Joe 100% (probably because we have discussed this offline in depth and he has moulded my opinions <g> ). Smaller environments don't need to worry about it. Big environments need to think about it. Although, as Joe mentions, it's rare you'll need much space for the log files. Even if you provision a couple of hundred thousand users (which takes an hour or two) you don't need much space for logs. Which is why I hate the 3x RAID1 idea that is out there. Disks are cheap for sure, but that's still a serious waste of two disks where they could be put to use for the DIT, which is being slammed with read requests. Also remember that in smaller environments, or medium-sized environments that have didicated DCs, a DL360 (or equivalent) which only has room for two local disks, will happily run as a DC. A couple of the smaller projects I've worked on in the past (~7,000 users) we used just this. Although in some of those we had to use DL380s at some of the branches as they were also running Exchange! : ( One other thing I'd like to say here, is if you do need to worry about separating your disks, then you really should be looking at x64. You get better throughput with x64 on disk and memory access, and you also have the ability to get all, or at least a chunk of, your DIT data (as in objects that matter to your and your queries) into RAM. Those disk specs above are being implemented with x64 dual-core, dual-proc systems with 32GB of RAM as our standard DCs. (What can I say, I have a reasonable sized DIT ;-) (or so I'm told...) --Paul ----- Original Message ----- From: "joe" <[EMAIL PROTECTED]> To: <ActiveDir@mail.activedir.org> Sent: Tuesday, October 17, 2006 5:36 AM Subject: RE: [ActiveDir] Seperating Database and logs on seperate disks >I am surprised there aren't more responses to this. > > My personal opinion is that a vast majority of installations don't need to > separate off the logs for perf. In fact, I have often recommended running > everything on a single RAID 0+1/10/5 (partition logically if you want to > say > separate off the OS and the AD stuff) to get better perf than splitting > logs > and OS off onto their own disks. Especially in larger orgs for Exchange > GCs > that tried to follow the deployment docs and do mirror, mirror, mirror or > mirror, mirror, 0+1 but didn't have enough disks to get a good 0+1. > > In every case that I have had to review DCs with questionable disk > subsystem > perf, the issues are always around the DIT while the disks for the OS and > the Logs are snoozing with IOPS sitting there not being used that could > have > saved the DIT from getting sucked into the mud. Rebuilding the disk > subsystem with all disks in one of the above configurations has alleviated > the issues in every case. Whether RAID 5 or 0+1/10 is faster you will want > to test with your own disk subystems (say with IOMETER), it seems to vary. > I > have seen RAID-5 faster and I have seen on different machines 0+1/10 > faster. > > > A case I am aware of where the logs definitely were good off on their own > and would have seriously impacted perf if they weren't was Eric's DIT > experiment where he built a 2TB DIT but he was adding objects at a very > high > rate of speed constantly for quite a while so the logs were being beaten > pretty well. > > joe > > > -- > O'Reilly Active Directory Third Edition - > http://www.joeware.net/win/ad3e.htm > > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of AD > Sent: Monday, October 16, 2006 11:29 AM > To: ActiveDir@mail.activedir.org > Subject: [ActiveDir] Seperating Database and logs on seperate disks > > Is there any other reason other then performance to have the Active > Directory log files and database on separate disks? > > Opinions are welcome. > > Thanks > > Yves > List info : http://www.activedir.org/List.aspx > List FAQ : http://www.activedir.org/ListFAQ.aspx > List archive: http://www.activedir.org/ml/threads.aspx > > List info : http://www.activedir.org/List.aspx > List FAQ : http://www.activedir.org/ListFAQ.aspx > List archive: http://www.activedir.org/ml/threads.aspx List info : http://www.activedir.org/List.aspx List FAQ : http://www.activedir.org/ListFAQ.aspx List archive: http://www.activedir.org/ml/threads.aspx List info : http://www.activedir.org/List.aspx List FAQ : http://www.activedir.org/ListFAQ.aspx List archive: http://www.activedir.org/ml/threads.aspx
