Hi All,

Reading the forums and the like this seems to be the "best fit" settings for iSCSI tuning.

headerDigest=None
DataDigest=None
maxoutstandingr2t=8
FirstBurstLength=65536
MaxBurstLength=16776192
maxRecvDataSegmentLen=262144
InitialR2T=No
ImmediateData=Yes
Maxxmitdatasegment=262144
Wthreads=8

When comparing these settings to my ESXi 4.1 iSCSI advanced options I've listed the ones below that can be changed/already set (which I have updated yet)
headerDigest = Prohibited
DataDigest = Prohibited
MaxOutstandingR2T = 1
FirstBurstLength = 262144
MaxBurstLength = 262144
maxRecvDataSegLen = 131072
InitialR2T = unchecked
ImmediateData = checked

My first question is on ESXi 4.1 where do I check/set these 2 settings
Maxxmitdatasegment=262144
Wthreads=8

The second part is what happens if they don't match? will iSCSI just not work? or can it negotiate the settings?

I would like to make the tuning changes to my secondary DSS node, then make the changes to ESXi hosts, (hopefully with out knocking out the iSCSI side of things), manually failover to the secondary node, make the tuning changes to the primary, sync and fail back.

or do I have to bring everything down and change both with a completely offline system?

Cheers
Adam