Installation guide

C H A P T E R 9 Storage and File Systems
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Note: A VMFS volume that is used for failover-based clustering should have its mode
set to shared.
Writable — When virtual machines access a file on a shared VMFS, the file system
metadata becomes read-only. That is, no virtual machine or user command can
create, delete or change the attributes of a file.
If you need to create, remove, or change the length of a file (vmkfstools -X), then
you need to change the volume to “writable”. First, be sure that no virtual machines
are accessing the VMFS volume (all virtual machines are powered off or suspended),
then change the file system metadata to writable with the command, vmkfstools
--config writable. Once you power on or resume a virtual machine, the file
system metadata reverts to being read-only.
Extends an existing logical VMFS-2 volume by spanning multiple partitions
-Z --extendfs <extension-SCSIDevice>
-n --numfiles #
This option adds another physical extent (designated by
<extension-SCSIDevice>), starting at the specified SCSI device. By running
this option, you lose all data on <extension-SCSIDevice>.
Note: A logical VMFS-2 volume can have at most 32 physical extents.
This operation is not supported on the VMFS-1 file system and in fact, returns an error
if the specified SCSI device is formatted as VMFS-1. Each time you use this option and
extend a VMFS-2 volume with a physical extent, the VMFS volume supports, by
default, an additional 64 files. You can change this default number of files by using the
-n option.
Maps a Raw Disk or Partition to a File on a VMFS-2 Volume
-r --maprawdisk <raw-SCSI-device>
Once this mapping is established, you can access the raw disk like a normal VMFS file.
The file length of the mapping is the same as the size of the raw disk or partition. The
mapping can be queried for the raw SCSI device name by using the -P option.
By mapping a raw disk or partition to a file, you can manipulate this raw disk or
partition as any other file. In addition, this mapping enables you to have undoable,
append, and nonpersistent “raw disks”.
All VMFS-2 file-locking mechanisms apply to raw disks.