Specifications

Table Of Contents
VMware, Inc. 165
Chapter 7 Using High-Availability Configurations
! At!this!time,!if!one!virtual!machine!does!not!have!SCSI!reservation!enabled!for!its!
virtual!disk,!but!another!virtual!machine!does!have!SCSI!reservation!enabled!for!
the!same!virtual!disk,!VMware!Server!does!allow!the!disk!to!be!shared.!However,!
any!virtual!machine!not!configured!for!SCSI!reservation!that!tries
!to!access!this!
disk!concurrently!can!cause!corruption!or!data!loss!on!the!shared!disk.!VMware!
recommends!you!take!care!when!sharing!disks.
! If!you!need!to!shrink!or!defragment!the!virtual!disk!(which!can!be!done!only!with!
a!growable!virtual!disk),!first!disable!SCSI!reservation!and!make!sure!the!virtual!
disk!is!not!being!used!by!any!other!virtual!machine.!
To!disable!SCSI!reservation!for!all!SCSI!disks!in!a!virtual!machine,
!open!the!
configuration!file!and!comment!out!or!remove!the!scsi<x>.sharedBus =
"virtual"!line!and!make!sure!the!disk.locking!line!is!set!to!"true".
To!disable!SCSI!reservation!for!only!a!specific!SCSI!disk!on!a!shared!bus,!change!
the!scsi<x>:<y>.shared = "true"!line!in!the!configuration!file!to!
scsi<x>:<y>.shared = "false".!You!can!also!
comment!out!the!line.
! In!a!Windows!virtual!machine,!some!disk!errors!are!recorded!in!the!Windows!
event!log!in!normal!operation.!These!error!messages!have!a!format!similar!to
"The driver detected a controller error on \Device\Scsi\BusLogic3"
The!errors!should!appear!in!the!log!periodically!only!on!the!passive!node!of!the!
cluster!and!should!also!appear!when!the!passive!node!is
!taking!over!during!a!
failover.!The!errors!are!logged!because!the!active!node!of!the!cluster!has!reserved!
the!shared!virtual!disk.!The!passive!node!periodically!probes!the!shared!disk!and!
receives!a!SCSI!reservation!conflict!error.
Overview of Clustering with VMware Server
VMware!Server!clustering!capabilities!are!ideally!suited!for!development,!testing,!and!
training!applications.
NOTE Always!rigorously!test!and!review!your!cluster!before!deploying!it!in!a!
production!environment.
This!section!includes:
! Applications!That!Can!Use!Clustering”!on!page 166
! “Clustering!Software”!on!page 166
Clustering!provides!a!service!through!a!group!of!servers!to!get!high!availability,!
scalability,!or!both.