pesinet
Contributor
Contributor

I have better performance in Local SCSI Storage than iSCSI SAN!!!!!!

Hello guys,

When we build our first storage was local SCSI in a Raid 5 because we don't have a iSCSI SAN and the performance was great but now we have a iSCSI SAN HP MSA 2012i software solution and the performance on the Terminal Server are very poor. The firmware on the SAN is up-to-date and the HDDs too. We talked with HP and said that so far we have well configure the SAN. We had to pull off the Roaming Profiles from the SAN because when the user try RDC to connect to our network said "insufficient resource and cannot load the roaming profiles"?

Any idea?

Thanks

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Chuck8773
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Hot Shot

How is the server connected to the SAN? Though software iSCSI or through a VMDK file?

Charles Killmer, VCP

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pesinet
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Contributor

through the iSCSI software on the VMware Host

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Chuck8773
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Hot Shot

So either an RDM or a VMDK file. Ths explains it. ESX 3.5 can use only a single connection to the volume. I assume you don't have 10 Gbps network? This means that the max throughput to the SAN is 128 MBps. Depending on the type of disk IOPS will be quite lower. In my experience, if you are using SATA disks, you will see around 900 IOPS. SAS disks will get you around 4000 IOPS.

That local SCSI controller will likely hit 300 MBps and 2000 IOPS. So your large sequential IO will be quite slower as will your IOPS.

We remedied this in a few ways. Use SAS disks in the SAN when connecting the host to the SAN. Use an iSCSI initiator within the VM and use multiple vNics to acheive more than 1 Gbps throughput. Or upgrade to ESX4. ESX 4 lets you multipath to the SAN. I have seen huge performance increases with this feature alone. I do not have numbers yet as it is only in our test lab with a lower performing SAN. But that lower performing SAN outperforms our production SATA SAN under ESX 3.5 U4.

Charles Killmer, VCP

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pesinet
Contributor
Contributor

Thanks, in the mean time we move back the VMs from the SAN to the host local storage to avoid the network congestion. BTW the all the SAN's HDD are SAS

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mvarre
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Contributor

I am using an MSA2012i with 450GB 15K SAS drives, and though I'm not really throwing alot at it , just about 6 softly used servers including a 50 user exchange server, I'm extremely please with the performance thus far. (the usability of the interface is another issue)

I'm running mine in RAID50 - i wouldnt recommend RAID5 for the sort of load on the MSA. Just my 2 cents.

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pesinet
Contributor
Contributor

We have around 150 concurrent users and running Terminal Server and the performance is quite low.

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Chuck8773
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Hot Shot

Disk is crucial for Terminal Servers. I would start evaluating vSphere 4 and move back to local disk in the mean time. After ESX4, set the connection to the SAN with 4 or more MPIO connections.

Charles Killmer, VCP

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