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2898
January 11th, 2010 14:00
Slowness issues with AX150i
Hello,
We recently migrated to a new file server environment using a PE2850 connected via ISCSI to an AX150i. Since the migration, we have had numerous complaints from our users regarding slow file access times, and we’re seeing Event ID 1509 on our Citrix servers everyday when the roaming profiles fails to load from the file server to Citrix.
We ran an perfmon on the file server over a 48 hour period. The results show that the disk queue length for drive D: (which is the drive that hold the user shares and the roaming profiles) has numerous spikes throughout the day, and often plateaus and hold at 6+. % Disk Time also has numerous spikes and holds above 90% at times.
The server is running Windows Server 2003 R2. PowerPath 4.5.1 installed. I’ve tried upgrading to PP 5.2, but was unable to get the shares to appear after reboots, even with the dependency and MPIO reg fixes from Dell Support.
I’m looking for any ideas to get this environment to work better. Please help. Thanks!
Dev Mgr
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9.3K Posts
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January 11th, 2010 14:00
What's your raid setup?
Raid 5 has pretty poor performance if you IO load is fairly high on the write side. Obviously the 7200rpm drives don't help this either.
You mentioned Citrix... if you are virtualizing, I'd let Citrix Xenserver handle all iSCSI instead of putting more processor cycles in a virtual machine. It also eliminates the need for Powerpath and such (not that Powerpath is 'bad', but if you don't have to run it (because Xenserver handles MPIO), why add yet another driver to the mix?
cdady
7 Posts
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January 12th, 2010 06:00
We do use Raid 5, spread across the first four drive in the device. However, comparing the read and write queues from the perfmon, we're doing about 8x the number of reads compared to writes. Would adding additional drives to the Raid 5 container give us better performance on writes.
Thanks.
Dev Mgr
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9.3K Posts
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January 12th, 2010 06:00
With that ratio of reads to writes (8:1), the raid 5 parity performance hit isn't as noticable.
The easy way would be to buy some AX150 drives (this system won't accept generic drives) and add them, but I think that moving the iSCSI from the VMs to the physical server (so from Windows to Citrix) may make more of a difference.
cdady
7 Posts
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January 12th, 2010 06:00
The chassis is already full, so I can reconfigure the container with more drives.
I'm not sure what the second part of your post is referring to. The file server is the only thing that connects to the storage device, and it is physical. The Citrix Presentation Server are virtualized (on Hyper-V right now), and they are having issues because they can't load the TS roaming profiles from the file server successfully. The profile share, along with the three other network drive shares, is on the D: drive on the server, which is on the AX150i.
Is there a best practice document for configuring a Windows Server 2003 install to connect with an ISCSI device? I concerned that we missed something in the server, NIC, or network setup that may also be affecting performance. For instance, I'm unable to find definitive info on whether or not TCP/IP Offload should be enabled for the ISCSI NIC's on the Windows file server.
Thanks.
cdady
7 Posts
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January 12th, 2010 10:00
We have just one machine connecting to the storage device over ISCSI. A Dell PE2850 in a file server role. It connects via a dual NIC PCI card on a private ISCSI VLAN.
Dev Mgr
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9.3K Posts
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January 12th, 2010 10:00
What kind of servers/systems are connecting (via iSCSI) to the AX150i? Are they physical machines or virtual machines? If virtual, move the iSCSI part to the physical machine(s) and let the virtual machines just get storage from the management OS (Windows 2008 if you're using the hyper-v role in a 2008 server).