Is there any sort of utilization stats on the EVA? Frankly I wouldn't expect 21 spindles RAID5 to perform very well at all with a mixed workload like this.
Thanks, Brian Desmond br...@briandesmond.com c - 312.731.3132 From: Mark Milo [mailto:markmilo2...@gmail.com] Sent: Monday, November 01, 2010 9:14 PM To: NT System Admin Issues Subject: Re: Virtual Machine Disk Configuration The san has 21 FC disks configured as a raid 5 array. There have two luns configured from this array. All 15 guest machines are located on one of these luns (including exchange). The performance hit appears mainly on exchange but other servers are suffering as well. The interesting thing is that IOPS for the entire lun holding the 15 VM's is only around 600 at the time that the disk busy is around 95%. The disk queue for that lun is around 4 - I will need to set up longer term monitoring to get the read/write times when the disk set gets busy (which is usually first thing in the morning) On Tue, Nov 2, 2010 at 12:35 PM, Sean Martin <seanmarti...@gmail.com<mailto:seanmarti...@gmail.com>> wrote: We'd need a lot more info. Start with your disk configuration. How many disks make up the storage pool or raid group the exchange lun is allocated from? Are there other luns allocated from the same pool? How many? Which exchange resources reside on the lun (stores, logs, etc.)? Disk busy warnings buy themselves don't hold much weight, unless of course there are noticeable performances issues, which you alluded to. You'll want to capture disk queue and disk latency stats ( avg disk queue length and avg disk sec/reads and writes). Avg queue depth should below X (where X equals the number of physical disks. Read/write times should avg below 20ms and not spike above 50ms. I'd also recommend running the exbpa and the troubleshooting assistant. If you can gather I/O stats you may be able to determine if the disks can handle the load. If it doesn't appear Exchange is stressing your resources, you may need your SAN monitoring tools to determine if total I/O (assuming multiple luns share the same disks) are more than the disks can handle. I'm not familiar with EVAs, but overloading disks in a SAN can lead to cache flushing which could affect performance of the array itself. - Sean On Nov 1, 2010, at 5:08 PM, Mark Milo <markmilo2...@gmail.com<mailto:markmilo2...@gmail.com>> wrote: The host is Windows 2008 R2 running Hyper V. The performance is monitored via UPTIME monitoring software but I see similar high reading using perfmon (%disk time). Don't see any error messages at high utilization but the exchange 2003 server is responding poorly when disk is busy. There are 15 guest machines on this particular host but most of them dont use too much in the way of resources. On Tue, Nov 2, 2010 at 11:51 AM, Richard Stovall <rich...@gmail.com<mailto:rich...@gmail.com>> wrote: On Mon, Nov 1, 2010 at 8:33 PM, Mark Milo <markmilo2...@gmail.com<mailto:markmilo2...@gmail.com>> wrote: Hi - I am having issues with "disk busy' on my virtual server host. The host is a DL 580 connected via fiber to an EVA 4400 SAN. Where do you see this message? On the VM? I understand that guest VM's should have disk layouts as per an equivalent physical machine... I don't really know what you mean by that. Can you elaborate a bit? ...but is it best practice to have a separate LUN per guest VM? Not that I've ever heard of. You'd have a management nightmare on your hands pretty quickly if you had a large number of VMs. If so what should the max utilization of the disk on that LUN be? I don't know of a hard and fast number/rule, but if you're using snapshot-based backup method (such as VCB) you definitely need free space on the LUNs for the snapshots to grow until the backup is finished and the snapshots can be eliminated. What virtualization platform are you running? 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