Does ESXi Host local storage have performance impact on VM over iSCSI?

[martinfnicman]

Hello,

Can anyone provide any information on the performance impact on the VM with different local drives speed for the host where VMs are using storage via iSCSI?

Our setup:

esxi 6 with local storage RAID1 with 2 x 300GB 7200 RPM

Dell Poweredge R610 with 10Gb intel X520 NIC, dual x5680, 96GB ram 1333.

VMs booted and using storage via software iSCSI (using NetApp as storage source) over 10Gb NIC.

Is there any documentation that explain performance impact when using different drives for the host os?

For example if replace 7200 RPM drives with 10k, 15k or SSD for the ESXi host and keep the VMs on the software iSCSI will this increase overall performance of the VMs or it will not make any difference?

Thanks,

Martin

[rcporto · Accepted solution]

If all virtual machine disks (and .vswp files) resides on the iSCSI datastore, replacing the local ESXi disks for faster disks will no make difference, unless you use some SSD for Flash Read Cache (read more about: http://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/techpaper/vmware-vsphere-flash-read...).