This is a follow-up to my previous post on the 5.0U2. At the same time, VMware also released vCenter 5.1.0b. This post will look at the storage items which were addressed in that update, although the issues that are addressed in the storage space are relatively minor compared to the enhancements made in other areas. Note that this update is for vCenter only – there is no ESXi 5.1 update.
Storage DRS & Storage I/O Control
In my series of posts on vSphere 5.1, I mentioned a new feature called VMObservedLatency which is now used by Storage DRS for performance metrics. This new counter is only collected on ESXi 5.1 hosts. It is not available on ESXi 5.0 hosts. Therefore if you have a mixture of 5.0 & 5.1 hosts, you can have some strange behaviour with Storage DRS & Storage I/O Control. The recommendation is to upgrade all your hosts to 5.1 if you wish to use I/O metrics with Storage DRS.
Storage vMotion operations can fail on busy VMFS datastores with an error “A parent disk path is required for snapshot of disk /path/to/disk/XXX.vmdk“. This is because a file open operation can take too long to complete on a very busy VMFS datastore. To avoid this error, the option diskLibMiscOptions.openRetries in the /etc/vmware/config file can be increased to reflect the number of open disk retries e.g. set it to a large number such as 99. This can avoid future failures.
2TB Virtual Machine Disks
The vSphere Web Client only creates VMDKs to a maximum size of 2TB-1MB. The maximum supported VMDK size is 2TB-512 bytes. If you want to create the maximum support size, use the vmkfstools command to create the virtual disk with the size of 2TB-512Bytes: vmkfstools -c –createvirtualdisk disk_size
Read the complete release notes for vCenter 5.1.0b for further information.