Aggrofish
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Contributor

ESXi 5.5 - iSCSI storage performance

Afternoon everyone,

I just wanted to pose a quick question about the poor performance I am experiencing between my 3 ESXi hosts and SAN storage.  We use iSCSI to connect to a Tegile Zebi 3100 hybrid flash array.  Connection speed is 1Gb.  Basically everything from backups, we recently started using Arcserve UDP, to migrating VMs from one datastore to another is very slow.

We did have a problem with some incorrect path selection policies being set on the datastores, once changed performance did improve but things are still a bit on the slow side.  I've used esxtop to check datastore and VM performance but nothing really jumps out.  Yes we do have some busy VMs but there doesn't seem to be anything to out the ordinary.

One thing I have noticed is on the vswitch for iSCSI.  There is a single nic configured for the service console and  a single nic for the iSCSI connection.  Would it be recommended to use more than one nic for iSCSI traffic?  Is there anything else I should check?

A bit more information.  We have three DELL R630 hosts with 256Gb memory and Intel Xeon E5-2670 CPUs.  Across the hosts there are currently around 80 VMs.

Any questions please come back to me.

Thanks,

Ross

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a_p_
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With 1 GBit/s networking, it definitely makes sense (not only for redundancy purposes) to use multiple NICs for iSCSI traffic. The number of initiator ports (# of NICs per host) depends on the number of target (storage) ports. Also keep in mind that the max. number of paths to a single LUN for software iSCSI is 8 per host (see https://www.vmware.com/pdf/vsphere5/r55/vsphere-55-configuration-maximums.pdf). Assuming that your storage systems supports Round-Robin, you should see a far better thoughput with multiple NICs. What you may also want to consider - unless already implemented - is configure Jumbo frames for the storage traffic.


André

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a_p_
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