When I read VMware documents, there is a cool feature Hardware Acceleration I found in storage book. That recall me an outage about one year ago, our NetApp filer was crashed due to motherboard problem, part of datastores was failed, we have to move virtual machine from the filer to other. We noticed the storage vMotion performance was pretty high, the data moving speed was 2 times less than regular storage vMotion. That’s the advantage of Hardware Acceleration.
The first thing of this year is standardize the virtualization environment. I found an interesting problem when I checked the Hardware Acceleration part, same luns show different status on different ESXi 5 host of a cluster, some of the hosts show Hardware Acceleration enabled, and some show Unknown.
The storage is EMC Clarion CX series with ALUA enabled, I found working hosts attached VAAI filter, non-working hosts had nothing.
Figure 1 Working Host
Figure 2 Non-working Host
ESXi 5 automatic attach different filter according to lun properties, that issue indicates the lun properties was different on different ESXi 5 host, that’s a storage layer issue, after troubleshooting with EMC, we found Failover Mode of luns was different on each host, the Failover Mode should be 4 instead of default 1.
Please be aware of that storage activity on particular host will interrupt when you change Failover Mode, please put the host in maintenance mode first.
Regarding Failover Mode, I had discussion with a storage engineer, he told me different storage vendor have different name for “Failover Mode”, some storage vendor may request choose OS type of target machine. For EMC, there are 5 modes, please refer to page 10 on EMC document