[THIN] Re: RAID 1
- From: "Nick Smith" <nick@xxxxxxxxxxxxxxxxxx>
- To: <thin@xxxxxxxxxxxxx>
- Date: Wed, 2 May 2007 10:16:36 +0100
Sorta connected, we had a discussion a while back about SAS vs SATA drives in a TS setup. There were some strong feeling that SATA were junk, but I don't remember any conclusive evidence that you got lower performance in terms of session numbers/performance. Anyone done more testing and/or have feedback from live production? Nick From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf Of Joe Shonk Sent: 01 May 2007 21:51 To: thin@xxxxxxxxxxxxx Subject: [THIN] Re: RAID 1 I understand RAID 0 and RAID 1... Just with RAID 1 (mirroring) you need a even number of drives... Joe On 5/1/07, Dupris, Mike <Mike.Dupris@xxxxxxxxxxxx<mailto:Mike.Dupris@xxxxxxxxxxxx>> wrote: Andrew: You're the best! Thanks for listening and weighing my contribution to the string -albeit I should have used the designation Mirror and Stripe rather than null and one; thankfully you understood my message [hopefully I was consistent in err ;) ] Thankfully we have people and processes whose algorithm includes perception... NUTSHELL: Striping performance over mirror is NOTICABLE. Try this write up: http://www.microsoft.com/technet/prodtechnol/windows2000serv/reskit/core/fndb_con_dwtx.mspx?mfr=true I guess, the most applicable documentation for you would be to image your server as is, then setup your disks mirrored and then drop down the image and setup a performance monitor. Next you setup your disks striped and setup the same performance monitor. Finally for a baseline setup the server on one single disk (cut up the disk to emulate the patricians) and record with performance monitor -that is if you are truly interested in knowing actual performance gains applicable to your environment as the only change (remember you are using an image) is the disk configuration. You asked, there's the real answer -no formula can tell you exactly how your server is going to perform until you slap down all the applications and configurations on the same box. You probably have seen the wiki (http://en.wikipedia.org/wiki/Standard_RAID_levels ), there are some formulas for you to scribble down and put in your ROI documentation. I suppose factors that would influence the write up and is not documented would be performance gain from disk speed and caching. But from personal experience supporting 1000-10,000 employee companies and enterprise internet forward-facing NT clustered environments (we average being in the top 100-500 on the internet) [that is NOT me boasting but just information about my background and environments I have been in -the solutions and configurations I have tried successfully- I put it in there to give you an idea of what type of situations I have built and supported, I do not know where you are coming from and what types of constraints you have] Striped NOS volumes with a dedicated disk for temp files have consistently and noticeably out performed data-redundant volumes [a separate patrician will not be as fast for temp files but yes, it will give you a performance nudge.] What can you do though about a disconnected Citrix user -no matter what they are working on they will be miffed. What happens to fifty disconnected users is Citrix issue at heart not necessarily a Hardware, Software or configuration change issue; elaborated: Say if you have an environmental variable beyond your control at location A, Citrix is not intelligent enough to seamlessly transfer a User and their Environment to location B or the Citrix Technology may not have the opportunity to transfer the User and Session to another location in time; therefore you will ALWAYS have the possibility for downtime. Every computer (regardless of workstation or server) can crash or have the unforeseen occur to it -you need to be able to convey that to your end users and clients. NOTHING ever in computers is absolute. I understand why Citrix would be the dominate topic; however, I thought this was a Terminal Server string -so that's why I offered the configuration. Joe: You will have to read the documentation that came with your box to configure, but here is the concept to your answer: http://www.microsoft.com/technet/prodtechnol/windows2000serv/reskit/core/fndb_con_dwtx.mspx?mfr=true Table 11.3 Structure of a Striped Volume Stripe Number Disk 1 Disk 2 Disk 3 Disk 4 Stripe 1 1 2 3 4 Stripe 2 5 6 7 8 Stripe 3 9 10 11 12 Stripe 4 13 14 15 16 Stripe 5 17 18 19 20 Some places are setup for PXE boot (meaning they boot off a SAN so no disks are needed on the server itself); therefore the disks are not necessary on the blade server and you can dedicate as many disks and configure the disks in whatever manner you choose. Mike Dupris From: thin-bounce@xxxxxxxxxxxxx <mailto:thin-bounce@xxxxxxxxxxxxx> [mailto:thin-bounce@xxxxxxxxxxxxx<mailto:thin-bounce@xxxxxxxxxxxxx>] On Behalf Of Andrew Wood Sent: Tuesday, May 01, 2007 3:47 AM To: thin@xxxxxxxxxxxxx<mailto:thin@xxxxxxxxxxxxx> Subject: [THIN] Re: RAID 1 Well - I knew you meant RAID0 when you wrote RAID1 and vice versa - I see what you did there, keep everyone on their toes and make sure we're paying attention. I see I'm not the first to comment, so I take it I've not won the £5 L My "issue" is that for blades/1U servers (which is not an uncommon config for a citrix/ts server) what *is* the performance difference for a RAID1/RAID0/separate drives - is it significant? Yes, technically, when you've multiple spindles you get a better performance - but, what does that better performance relate to in the real world? You've only two drives - how much 'better' is 'better'? I would typically configured a RAID1 config as it's the more reliable - but, what I've not had chance to do is take a couple of servers, build raid1/raid0/separate drive configs and then load them up which performs better. And then 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. Yes - that's right and dandy for, say, a SQL or exchange backend - but perhaps that's of little use to you if your citrix server goes off-line with 50 concurrent users. Punters may well be able to reattach on another server in the farm - but only after they've hunted you down and maimed you with a rusty spoon as they've lost the end of year financial data they were working on at the time... yet ...is the risk of that happening worth taking given the (possible) performance increase that you've gained by dropping raid1 and using raid0? I'm more than willing to accept a short contract for me to muck about with this and bring back findings if anyones interested J From: thin-bounce@xxxxxxxxxxxxx <mailto:thin-bounce@xxxxxxxxxxxxx> [mailto:thin-bounce@xxxxxxxxxxxxx<mailto:thin-bounce@xxxxxxxxxxxxx>] On Behalf Of Dupris, Mike Sent: 30 April 2007 22:30 To: thin@xxxxxxxxxxxxx<mailto:thin@xxxxxxxxxxxxx> Subject: [THIN] Re: RAID 1 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> [mailto:thin-bounce@xxxxxxxxxxxxx<mailto:thin-bounce@xxxxxxxxxxxxx>] On Behalf Of Andrew Wood Sent: Monday, April 30, 2007 7:45 AM To: thin@xxxxxxxxxxxxx<mailto: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> [mailto:thin-bounce@xxxxxxxxxxxxx<mailto:thin-bounce@xxxxxxxxxxxxx>] On Behalf Of Joe Shonk Sent: 28 April 2007 15:38 To: thin@xxxxxxxxxxxxx<mailto: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<mailto: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 SBC SITES ONLY GOOGLE SEARCH: http://www.F1U.com<http://www.f1u.com/> ************************************************ For Archives, RSS, to Unsubscribe, Subscribe or set Digest or Vacation mode use the below link: http://www.freelists.org/list/thin ************************************************ This e-mail is confidential and is intended only for the attention of the addressee. If you are not the intended recipient, this e-mail should not be disclosed to any other person. 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- [THIN] Re: RAID 1
- From: Jez
- [THIN] Re: RAID 1