Slow file access

[Breslau]

Greetings,

I'm a SAN administrator and have had one of my users, a windows '03 server admin, come to me with reports of end user complaints of occasional slow file access. from what i can tell, there seems to be no pattern of when this problem occurs. we have done some basic attempts on the fibre channel side to address the issue, swapping cables, changing HBAs, setting the HBA's connection speed to a fixed rate, and tuning the disk controller.

unfortunately, the windows admin is not the type to dig into the OS to find out what's really going on, so i am looking for advice on where to look. something on the order of memory management and file caching. i come from a Unix background so i am not familiar how someone in the windows world would approach this...

any help would be appreciated!

TIA!

 

[itsp1965]

Does this server have local storage? Is it possible that the issue is not the SAN disk but local disk on the server?
Users are complaining that file access is slow. Things to take into consideration;

1. Is the server local to these users (same location/subnet). Is it all users who are complaining or just certain users. Could be a network related issue
2. On the SAN side.. how many LUNs are assigned to this server and what is the total size of the disk. Has the admin configured the volume as a spanned volume or has he created another RAID-5 volume (not required since you are relying on the SAN for your RAID)

If you have verified everything on the SAN side, I say it's time for your Windows admin to look at the server itself and not blame the SAN

Hope this helps.

 

[Breslau]

1. not 100% sure about that, i do know the network guys looked at the physical line at least one of the complaining users and the server use to connect to our LAN and did not find any errors related to the problem.

2. this box has a single LUN, 3 TB in size. the LUN is striped over several disks. i have not seen any errors logged to the SAN switch or the disk controller. the SAN hardware is not being pushed anywhere near its capacity.

"it's time for your Windows admin to look at the server itself and not blame the SAN"

at this point, i agree with that statement, and am looking for ideas and directions in which i can nudge the windows admin.

something along the lines of : have you checked this, this, or that?

 

[itsp1965]

Well Breslau, it shouldn't have to be your task to tell the Windows admin to look at this and that. You should be asking him what proof do you have that the SAN disk is at fault? Has he run any performance monitoring tool to substantiate the claim that it's the SAN's fault?
With that said;
- As I have indicated, have him run the Windows system monitor in order to ascertain whether there is an issue with disk perf
- Have him check the event logs on his server HBAs to see if there are any errors being generated

If nothing turns up then he is barking up the wrong tree in asking to pursue where it should be him doing the checking on his side.

 

[Breslau]

I think the problem is that they're not motivated to dig deeper. the user community just knowns when they're using the drive that they will occasionally have a problem, and it's just easier for the windows admin to point a finger at the disk subsystem.

you're right, i shouldn't have to troubleshoot server issues, and i really don't want to either. i just don't know the right questions to ask them in order to get them on the right track to actually solving the problem.

 

[itsp1965]

Breslau as per my last post.. have him prove that it's the SAN. If he is not willing to dig as you say then there is no problem