slow drive performance…

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    HP DL380 G4 server with (3) 146GB 15k SCSI RAID drives. RAID controller has 64mb memory and is set for 100%read/0%write.

    No problems whatsoever on this server for the last year/year and a half. Today however is a different story.

    I was asked by the CEO to change permissions on a bunch of shared folders. Previously, permissions were set at the NTFS level using AD global groups. That wasn’t adequate enough for the security she wanted, so she asked me to specify individual user accounts for a slew of directories and subdirectories.

    Now, maybe it’s just coincidence (or maybe I didn’t notice until now), but as soon as I started making the changes (or shortly thereafter), I noticed I was getting an hourglass (cursor) when trying to make changes to permissions, access folders, etc.

    It seems a bit dramatic that my disk drives would be causing the slowness just because I was requested to change permissions on a bunch of folders, but I ran W2003 performance monitor and sure enough, whenever I get an hourglass cursor, “Disk Time % – Write” goes up to 100% and Disk Queues also shoot up. “Disk Time % – Read” also goes up sometimes, but not nearly as often…

    As soon as the % Disk Time drops down from 100%, and the queue length drops down, the hourglass turns back into the cursor and server performance seems normal again.

    Prior to these changes earlier today, I did not (nor was it reported to me) notice any slowdowns or problems with the speed of the server…

    So… is changing NTFS permissions from global groups to specific users this detrimental? Sure seems to be – I’m quite shocked if that’s the case.

    I’m wondering how much improved it would be from upgrading the RAID controller to something that could cache writes, and not just reads, or something with a little more cache than 64mb. It would be difficult to convince her to go back to using global groups for NTFS permissions on some of these directories…

    Anyone experience something like this? I’m going to try and track down what specifically the drives are doing when the Disk Time % – Write goes to 100%, using programs like processmonitor.exe from SysInternals, but not having much luck yet…


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