Specifications

VMware, Inc. 301
Chapter 10 Configuration for Clustering
Substitute!the!name!of!the!appropriate!disk!or!VMFS!in!place!of!vmhba0:1:0:0.
Locking at SCSI Disk Level
The!second!kind!of!locking!is!locking!at!the!SCSI!disk!level,!which!is!called!SCSI!disk!
reservation.!
Any!server!connected!to!a!SCSI!disk!can!issue!a!SCSI!command!to!reserve!the!disk.!If!
no!other!server!is!reserving!the!disk,!the!current!server!obtains!a!reservation!on!the!disk.
!
As!long!as!that!reservation!exists,!no!other!server!can!access!the!disk.!All!SCSI!
commands!to!that!disk!by!other!servers!fail!with!an!appropriate!error!code.!
If!a!vmkfstools!command!is!attempted!on!a!VMFS!on!a!disk!that!is!reserved!by!
another!server,!the!vmkfstools!command!fails!
with!a!message:
vmkfstools: shared SCSI disk is reserved by another server. Use
'vmkfstools -L release/reset' to end reservation if no other server is
using the SCSI reservation
Similarly,!a!virtual!machine!fails!to!start!if!its!virtual!boot!disk!is!stored!on!a!physical!
disk!that!is!reserved!by!another!host.
Most!applications!do!not!ever!reserve!a!SCSI!disk.!However,!failover!clustering!
software!reserves!SCSI!disks!to!ensure!that!only!the!active!node!is!able!to!access!
the!
shared!SCSI!disk.!Expect!that!the!shared!disk!in!a!physical!clustering!setup!is!reserved!
when!the!cluster!is!active.!Similarly,!for!a!virtual!machine!cluster!that!is!running!across!
physical!machines,!reservations!by!the!clustering!software!are!transmitted!through!to!
the!physical!shared!disk.
If!you!encounter!a!disk!
that!is!reserved!unexpectedly,!try!to!determine!whether!some!
clustering!software!has!explicitly!reserved!the!disk.!If!not,!you!can!release!the!
reservation!on!the!server!that!has!the!reservation!by!running!a!command!in!this!format:
vmkfstools -L release vmhba0:1:0:0
Substitute!the!name!of!the!appropriate!disk!or!VMFS!in!place!of!vmhba0:1:0:0.!
If!you!cannot!determine!which!server!holds!the!reservation,!you!might!be!able! to!
eliminate!the!reservation!by!issuing!a!SCSI!bus!reset!on!any!server!machine!using!a!
command!in!this!format:
vmkfstools -L lunreset vmhba0:1:0:0
If!this!fails,!try!the!following!command:
vmkfstools -L reset vmhba0:1:0:0