Due to many performance studies about disk performance it is well known that disk alignment for both VMFS partitions and NTFS file systems improve IO performance such as reduced latency and increased throughput. Alignment of VMFS partitions are done when configuring storage via the VI client but aligning NTFS partitions in Windows system prior to Windows 2008 is a manual task.
Windows Server 2008 use a partition starting offset of 1,048,576 bytes (1,024 KB) for disk larger than 4GB. This provides a well enough alignment for most disks. According to the official documentation, windows 2008 uses a different partition starting offset for disks smaller than 4GB. Or as MS states in the document
Performance Tuning Guidelines for Windows Server 2008
“Note that Windows Server 2008 defaults to a smaller power-of-two offset for small drives.”
But which starting offset does W2K8 exactly use for smaller disks?
[Read more…] about Windows 2008 disk alignment
Flex-10 lessons learned
One of my clients bought a couple of HP blade c7000 enclosures recently. Including the new dual port Flex-10 mezzanine cards (nc532m) and Flex-10 Virtual Connect modules. Due to the fact that this technology is quite new, not much inside-info is found on the web. I’ve had lots of discussions with Ken Cline and Scott Lowe, which will publish an Flex-10 article by it’s own pretty soon. This write-up is a quick overview of lessons learned by me but even
more a call for answers.
[Read more…] about Flex-10 lessons learned
VMFS Volume Management document
VMware published an excellent document about VMFS volume management a few days ago.
VMware® VMFS Volume Management information guide
The guide explains the VMFS volume header metadata mechanism and describes the new 3.5 setting SCSI.CompareLUNNumber. A must read if you use third-party storage snapshot and replication technology.