Very true. Large global cache, automated tiering, etc. are all technologies that change the way performance and bottlenecks are measured. There are situations introduced in SAN environment (forced flushing of cache), that can occur in a DAS scenario, are much more prevelant in a SAN and have much wider impact. Looking at solutions like Compellent or 3Par that have virtualized storage add another level complexity. Your data could be striped across hundreds of drives. I wouldn't consider a queue depth at an equal number acceptable for a single volume.
- Sean On 2/7/12, Brian Desmond <[email protected]> wrote: > Gets more interesting with SAN though when you have something like a Netapp > FlashCache or something in the mix > > Thanks, > Brian Desmond > [email protected] > > w - 312.625.1438 | c - 312.731.3132 > > > -----Original Message----- > From: Paul Hutchings [mailto:[email protected]] > Sent: Tuesday, February 07, 2012 10:36 AM > To: NT System Admin Issues > Subject: RE: IOPS's calculations > > I don't think SAN vs. DAS/NAS should matter tbh, just the spindles in the > array - no expert either I just muddle by. > > This is what I was going from - > http://technet.microsoft.com/en-us/library/cc938625.aspx > ________________________________________ > From: Michael B. Smith [[email protected]] > Sent: 07 February 2012 4:25 PM > To: NT System Admin Issues > Subject: RE: IOPS's calculations > > I'm not a SAN expert. But for typical RAID subsystems, I don't want the > physical queue to exceed the number of disks in the array. If it does, then > I've got excessive queuing and degraded performance. > > I don't see how it would be different for a SAN, but I dunno. > > Regards, > > Michael B. Smith > Consultant and Exchange MVP > http://TheEssentialExchange.com > > > -----Original Message----- > From: Paul Hutchings [mailto:[email protected]] > Sent: Tuesday, February 07, 2012 10:40 AM > To: NT System Admin Issues > Subject: RE: IOPS's calculations > > Most guides I've read suggest if the LUN has 10 physical disks, you don't > want the queue to exceed around 20, or if you have 5 disks a queue of 10 and > so on. > > -----Original Message----- > From: Michael B. Smith [mailto:[email protected]] > Sent: 07 February 2012 15:06 > To: NT System Admin Issues > Subject: RE: IOPS's calculations > > Where do you get "x 2" ? I was with you - until that. > > Regards, > > Michael B. Smith > Consultant and Exchange MVP > http://TheEssentialExchange.com > > > -----Original Message----- > From: Paul Hutchings [mailto:[email protected]] > Sent: Tuesday, February 07, 2012 8:56 AM > To: NT System Admin Issues > Subject: RE: IOPS's calculations > > As a rule of thumb queue length shouldn't exceed the physical number of > disks in the array that the LUN is on x 2. > > -----Original Message----- > From: Kurt Buff [mailto:[email protected]] > Sent: 07 February 2012 13:50 > To: NT System Admin Issues > Subject: Re: IOPS's calculations > > So, to which counters should I be paying attention in such a situation, or > what should be the difference in interpretation? > > I've got a file server that's being extremely slow to back up, though daily > performance is adequate. > > I'm seeing disk queue length hit as high as 37, with 5 LUNS for the machine. > > Kurt > > On Mon, Feb 6, 2012 at 21:32, Brian Desmond <[email protected]> wrote: >> Those perf counters can be a bit misleading when you're looking at a >> SAN on the backend, though. >> >> >> >> Thanks, >> >> Brian Desmond >> >> [email protected] >> >> >> >> w - 312.625.1438 | c - 312.731.3132 >> >> >> >> From: Michael B. Smith [mailto:[email protected]] >> Sent: Monday, February 06, 2012 3:32 PM >> To: NT System Admin Issues >> Subject: RE: IOPS's calculations >> >> >> >> Disk Reads per second >> >> Disk Writes per second >> >> Average Disk Queue Length >> >> >> >> I'd track both logical disk and physical disk. >> >> >> >> Regards, >> >> >> >> Michael B. Smith >> >> Consultant and Exchange MVP >> >> http://TheEssentialExchange.com >> >> >> >> From: Reimer, Mark [mailto:[email protected]] >> Sent: Monday, February 06, 2012 3:56 PM >> To: NT System Admin Issues >> Subject: IOPS's calculations >> >> >> >> Hi folks, >> >> >> >> Thanks for all your help in the past. >> >> >> >> Looking at setting up a SAN. From my research, I think one thing to be >> aware of is current IOPS (disk). There are a number of sites that will >> help you determine IOPS based on what hard drives (and RAID >> configuration). My question is: Many of my current servers are light >> use. The IOPS that these servers are capable of is much greater than what >> is actually being used. >> >> >> >> So, in order to more properly size the SAN, is there a way to >> determine working IOPS? That is, what is actually being used? I assume >> Perfmon would help, and will need to log over a period of time (I >> think a week would be about right, to catch most scenarios). But what >> counters, and how to analyze those counters? >> >> >> >> Servers are Windows 2003. >> >> >> >> Thanks. >> >> >> >> >> >> Mark Reimer, A+, MCSA >> >> Servers & Networking Admin >> >> Prairie Bible Institute >> >> Box 4000 >> >> Three Hills, AB T0M-2N0 >> >> Canada >> >> Tel: 403-443-5511, Ext. 3476 >> >> Fax: 403-443-5540 >> >> Email: [email protected] >> >> www.prairie.edu >> >> >> >> >> >> ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ ~ >> <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~ >> >> --- >> To manage subscriptions click here: >> http://lyris.sunbelt-software.com/read/my_forums/ >> or send an email to [email protected] >> with the body: unsubscribe ntsysadmin >> >> ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ ~ >> <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~ >> >> --- >> To manage subscriptions click here: >> http://lyris.sunbelt-software.com/read/my_forums/ >> or send an email to [email protected] >> with the body: unsubscribe ntsysadmin >> >> ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ ~ >> <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~ >> >> --- >> To manage subscriptions click here: >> http://lyris.sunbelt-software.com/read/my_forums/ >> or send an email to [email protected] >> with the body: unsubscribe ntsysadmin > > ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ ~ > <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~ > > --- > To manage subscriptions click here: > http://lyris.sunbelt-software.com/read/my_forums/ > or send an email to [email protected] > with the body: unsubscribe ntsysadmin > > > -- > MIRA Ltd > > Watling Street, Nuneaton, Warwickshire, CV10 0TU, England Registered in > England and Wales No. 402570 VAT Registration GB 100 1464 84 > > The contents of this e-mail are confidential and are solely for the use of > the intended recipient. 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