Specifications

Table Of Contents
VMware, Inc. 151
Chapter 6 Using Disks in a Virtual Machine
host!computers.!The!I/O!issue!is!especially!noticeable!when!the!virtual!machine!is!
booting.
NOTE Performance!in!Windows!NT!guest!operating!systems!might!also!be!affected!
by!disk!fragmentation!on!the!host!computer.!For!details,!see!“Configuring!and!
Maintaining!the!Host!Computer.
Improving Performance
You!can!increase!performance!by!enabling!DMA!(direct!memory!access)!on!the!virtual!
hard!disk’s!IDE!channel!in!the!virtual!machine.!
If!you!have!a!virtual!disk!and!a!DVD/CDROM!attached!as!master!and!slave!to!the!
primary!IDE!controller!(channel!0)!and!you!want!to!enable!DMA,!power!off
!the!virtual!
machine!and!use!the!virtual!machine!settings!editor!(VM!>!Settings)!to!move!the!
DVD/CDROM!drive!to!the!secondary!IDE!controller!(channel!1)!at!IDE!1:0.!
You!can!enable!the!DMA!feature!after!you!finish!installing!Windows!NT.!You!must!
install!Service!Pack!3!or!higher!
in!the!virtual!machine!to!enable!this!option.
After!the!virtual!machine!is!running!Windows!NT,!insert!an!SP3!or!SP4!CD!in!the!drive!
and!run!DMACHECK.EXE!from!the!\SUPPORT\UTILS\I386!folder!on!the!CD.!Or!download!
DMACHECK.EXE!from!the!Microsoft!Web!site!
(support.microsoft.com/support/kb/articles/Q191/7/74.ASP).
Click!the!Enabled!option!for!the
!IDE!controller!and!channel!configured!for!the!virtual!
disk.!Typically,!this!is!channel!0!only,!unless!you!have!the!virtual!machine!configured!
with!multiple!virtual!disks!and!no!virtual!DVD/CDROM!drive.
As!noted!above,!you!should!not!enable!DMA!on!an!IDE!channel!with!a!virtual!
DVD/CDROM!drive!attached.