SANs and Excessive Disk Utilization?

pnutjam asks: "I work for a small to medium mental health company as the Network Administrator. While I think a SAN is a bit of overkill for our dozen servers, it was here when I got here. We currently boot 7 servers from our SAN, which houses all of their disks. Several of them have started to show excessive disk load, notably our SQL server, and our old domain controller (which is also the file/print server). I am in the process of separating our file/print server from our domain controller, but right now I get excessive disk load during the morning when people log on (we use roaming profiles). I think the disks need to be defragged, but should this be done on the servers, or on the SAN itself? When it comes to improving performance, I get conflicting answers when I inquire whether I would get better throughput from newer fibre-channel cards (ours are PCI-x, PCI-e is significantly faster), or mixing in some local disks, or using multiple fibre channel cards. Has anyone dealt with a similar situation or has some expertise in this area?"

Wrong side of the problem

[JamesTRexx]

Maybe you're looking at it all wrong.
You state that the disk load is high in the morning when everyone logs in with roaming profiles, which suggests to me that the roaming profiles are way too large.
Depending on the Windows versions used, move the contents of the "My documents" folder to their personal network shares (give them one if they don't have any), tell them to move data in their Desktop folder to that share and only create shortcuts, maybe even create a mandatory quota limit on the clients.
Check your favorite search site on "Windows reduce roaming profile size" for more tips.

Re:Who's San Box is it?

[Sobrique]

Really? I must admit, I'm surprised. SAN is just a way to attach disks over scsi. I've yet to see an array that allows you to defragment a volume (a host device). EMC Clariions will let you defrag raid groups, but that doesn't do anyhting more tham move the LUNs around on they physical devices.

Or are you perhaps thinking of NAS (Network attached storage) devices?

Re:Not enough information

[pnutjam]

I use Big Sister to monitor all my servers. I get nice graphs that show memory, CPU, network load, disk utilization, etc. I looked and looked at this trying to find the cause of my problems. People complained about slow login times, sometimes they would get temporary profiles because their roaming profile would time out. The also complained about slow access times in our SQL dependant EMR (Electronic Medical Records) system. All my graphs showed everything within an acceptable range.

I finally found an SNMP query for "disk load". This purports to be a percentage, but I've seen it showing way over 100, sometimes as high as four or five hundred. If it gets above 50 or 60 people start to complain. My disk load spikes in the morning when people are logging in, it generally goes to about 80% or higher on my graphs [google.com]. My SQL server doesn't have these problems and I have yet to find a suitable way of monitoring the SQL log where I think the problem is originating.