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SAN CX300

I have a SAN CX300 which has a 2GB backbone. Does that mean copying files between virtual machines whether they're on the same or different LUNS should be 2GB per minute? Our SAN is fibre channel.

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AGenMIS
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AGenMIS
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ianmellorCommented:
Hi,

The copying of data depends on weather the vm's are on the same host and vSwitch. If the vm's are same vswitch they copy at the bus rate of the server. Other than that they will use the pNIC's. The 2Gb is the speed to the disks, the storage subsystem.

Hope this helps,
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AGenMISAuthor Commented:
They are on the same vswitch but are on different host. If they are on the same host, will they copy data between each other faster?Also, can you elaborate more on the 2GB. I'm still confused on what the backbone speed references.

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ianmellorCommented:
Hi,

They are on different hosts so they will copy at the network speed. The 2Gb is the speed that your HBA's have access to the storage. It has 2Gb bandwidth to access the disc, I/O requests. That is not your network connection.

Cheers,
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ianmellorCommented:
Sorry, forgot to add, if they are on the same server they will copy faster. They won't use the network connection the copy happens in host memory.

Hope this helps.
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AGenMISAuthor Commented:
The 2Gb is the speed the ESX host has to access storage on the SAN? So the 2Gb is irrelevant when it comes to copying files back and forth from VM to VM. If I had a CX500 the backbone would be 4 Gbps. What performance increase will I see with 4 Gbps instead of 2?

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ianmellorCommented:
Hi,

In a way yes. It only affects disk access speed, if you have slow disk SATA and a 2Gb connection that would be slower than 15K SAS with a 2Gb link. Having a quicker link only gives you more capacity to your disks, more IOPS.

Cheers,
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AGenMISAuthor Commented:
In short, having a quicker link only gives you more IOPS on the virtual machines?
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ianmellorCommented:
Yes, but it is not the only factor.
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AGenMISAuthor Commented:
Do you have any documentation that explains all of this?

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ianmellorCommented:
Documentation on how vm's communicate with the network of SAN technologies?
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ianmellorCommented:
Hi,

Here is the VMware SAN guide

http://www.vmware.com/pdf/vsphere4/r41/vsp_41_san_cfg.pdf

Here is the ESX configuration guide, look under network

http://www.vmware.com/pdf/vsphere4/r41/vsp_41_esx_server_config.pdf.

Hope I have explained myself clearly.

Cheers,

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