Had an issue over the weekend, one of our mailbox servers kept bluescreening. This particular VM has the C: and D: on storage iSCSI SAN.
Tried running checkdisk on C: and it bluescreened as well. HyperV manager shows the error “Cannot connect to virtual machine configuration storage”
The D: drive is showing uninitialized in disk management, and gives an error when trying to initialize.
Started getting “Windows – Delayed Write Failed” messages. Compression is not turned on on the HyperV servers local storage.
The iSCSI connections are provided by HP Lefthand SAN, 2 node cluster. One of the SAN nodes went down yesterday.
HP Lefthand Support Phone Number
putty into SAN node : port 16022
2 Lefthand SAN nodes
Each has a single 100mbit link….
When we brought SAN2 back online state, issue was resolved
My assumption is that the SAN couldn’t replicate fast enough with the load they have with Exchange on them, plus replicate the changes to the other SAN node, so they were out of sync when the 1 SAN node went down thus causing issues.
In preperation for taking the VCP5 exam I have been doing a lot of reading on vSphere 5. One of the topics was VAAI which is vSphere Storage API’s for Array Integration(VAAI). After some Google searching, it appears that LeftHand SAN’s do support VAAI. So that is great news, since it can dramatically increase performance. What VAAI does it offload some of the storage tasks from the ESXi hosts, onto the storage array itself. Below are some more specific details of what it does and how it improves performance.
Array Integration allows for Hardware-Assisted Locking which locks on a per sector basis instead of locking the entire LUN. This can have a substantial increase in performance when a lot of changes in metadata occur, such as when many VM’s are powered on at once.
Hardware-Accelerated Full Copy allows for the storage itself to make entire copies on its own, without having to send any read/write requests through an ESXi host. Events such as cloning VM’s or deploying new VM’s from templates have a significant reduction in storage traffic between the ESXi host and the array.
Hardware-Accelerated Block Zeroing allows storage arrays to zero out blocks very quickly and speeds up the process of creating new VM’s and formatting virtual disks.
vSphere5 is also thin provisioning aware, and when coupled with VAAI allows you to reclaim dead space and give you advanced warning when approaching out of space conditions.
VAAI Performance Info
By default, VAAI is enabled and supported with ESXi 5 so nothing had to be done in vSphere 5 or on the P4500 SAN.