VMware

While working with ESX server, I have collected many useful pieces of information. On this page I will collect the most useful of that information.

Disk offsetting

x86 based disk partitions suffer from a track misalignment.  This has existed for years. Tracks on a disk are usually 64 or 128 blocks in size, but the first partition is usually started on block 63 (this affects most Operating Systems, including ESX and Windows).  This leads to a higher number of disk I/Os to access more blocks than may be necessary. Generally speaking, this isn't a problem for most systems. It can cause huge performance issues with high I/O systems, like database servers, disks that contain lots of little files and high I/O, and ESX VMFS partitions. The problem has been alleviated with VI3, as long as you use Virtual Center to create your VMFS partitions. Here's a document with more information, including instructions on how to do it: disk offset procedures.doc