VMware GSX 3 - Manual (Page 201)

C H A P T E R 7 High-Availability Configurations with VMware GSX Server
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• SCSI disks can be shared via SCSI reservation among virtual machines running on
the same host. This means that the configuration files for the virtual machines
must all be located on the same GSX Server host. However, the disk or disks the
virtual machines are sharing can be located remotely on a different host.
• A SCSI virtual disk can be located on a host with any type of hard disk (for
example, IDE, SCSI or SATA). A shared physical disk must always be a SCSI disk.
• GSX Server virtual machines currently support only the SCSI-2 disk protocol, and
not applications using SCSI-3 disk reservations. All popular clustering software
(including MSCS and VCS) currently use SCSI-2 reservations.
Enabling SCSI Reservation
SCSI reservation must be enabled in a virtual machine before you can share its disks.
VMware recommends you set up any shared disks on the same SCSI bus, which is a
different bus than the one the guest operating system uses. For example, if your guest
operating system is on the scsi0 bus, you should set up disks to share on the next
available bus, typically the scsi1 bus.
To enable SCSI reservation, make sure the virtual machine is powered off. Open the
configuration file (.vmx) in a text editor and add the line:
scsi<x>.sharedBus = "virtual"
anywhere in the file, where <x> is the SCSI bus being shared.
For example, to enable SCSI reservation for devices on the scsi1 bus, add the
following line to the virtual machine’s configuration file:
scsi1.sharedBus = "virtual"
This allows the whole bus to be shared and is quicker than specifying each disk
separately. However, if you do not want to share the whole bus, you can selectively
enable SCSI reservation for a specific SCSI disk on the shared bus. For example, if you
want to share a SCSI disk located at scsi1:1, add the following line to the
configuration file:
scsi1:1.shared = "true"
You must specify the same SCSI target (that is, scsi<x>:1) in the configuration file
for each virtual machine that is going to share the disk.
If SCSI reservation is enabled for the whole bus (that is, scsi1.sharedBus is set to
"virtual" ), then this setting is ignored.