I have found that we get some significant performance gains if we change the number of IOPS before switching paths to 100 from the default 1000. I understand that this setting will not persist through a reboot so I need to know where I can put a script that runs the esxcli command to set this parameter when the ESXi 5 host boots.
Can anyone help me out?
This seems to be persistent through reboots on ESXi 5.x, see this thread;
I'm currently doing loads of storage benchmarking so will test this myself tomorrow.
I understand that this setting will not persist through a reboot
Uh, what? It sure does persist if you set it via esxcli properly. There used to be a bug in ESX(i) 4.0 where the setting would not persist reboots like you described, but it's been resolved since 4.0 U2:
For devices using the roundrobin PSP the value configured for the --iops option changes after ESX host reboot
If a device that is controlled by the roundrobin PSP is configured to use the --iops option, the value set for the --iops option is not retained if the ESX host is rebooted.
This issue is resolved in this release.
Besides if it wasn't, why does your setting stay at 100 and not the default 1000?
Glad to hear this is fixed in ESXi 5.0. I had just heard of someone else using this and they had to modify the boot script so these settings would persist. They implemented this in ESXi 4.x so I'll be sure to pass along that this is now fixed in ESXi 5