HP XP20000XP24000 Disk Array - Manual (Page 31)

Shared Memory Requirements
XP Thin Provisioning requires its own dedicated shared memory for the V-VOL management area, which
is separate from the shared memory for XP Snapshot. The required shared memory will be installed by
your HP service representative.
Operating System and File System Capacity
Certain combinations of operating systems and file systems can reduce the file system capacity for XP
Thin Provisioning. The following table shows the effects of these combinations. For more information,
contact your HP service representative.
Table 13 Operating System and File System Capacity
Operating
System
File System Meta-Data Writing Capacity reduction
Windows
Server 2003
NTFS Writes the first meta-data. Yes
Linux XFS
Writes the meta-data in the
Allocation Group Size units.
Yes
If the Allocation Group Size
setting is 640 MB when you
create the file system, the page
size is 42 MB, and the ratio will
be 42 MB ÷ 640 MB = 6.5%.
Therefore, pool capacity, which
is as much as 6.5% of the V-VOL
capacity, will be used when you
create the file system. There will
be no reduction if the setting of
the Allocation Group Size is too
small.
Ext2
Ext3 Writes the meta-data in 128 MB
increments.
Yes
However, pool capacity, which
is about 30 % of the V-VOL
capacity, is used to create the file
system.
Solaris UFS
Writes the meta-data in 52 MB
increments.
No
VxFS Writes the first meta-data. Yes
AIX JFS
Writes the meta-data in 8 MB
increments.
No
If you change the Allocation
Group Size settings when
you create the file system,
the meta-data can be written
to a maximum of 64 MB.
Approximately 65 % of the pool
is used.
JFS2 Writes the first meta-data. Yes
VxFS Writes the first meta-data. Yes
HP-UX JFS (VxFs) Writes the first meta-data. Yes
HFS
Writes the meta-data in 10 MB
increments.
No
Note : There will be less reduction if the volume capacity is too small. For example, if the V-VOL capacity
is 100 MB when you use Windows 2003 or NTFS, the first page (42 MB) will be assigned. Therefore,
XP24000 Thin Provisioning Software User's Guide 31