HP StorageWorks XP48 Disk Array - Manual (Page 63)

Working With OS-Based Constraints 63
• A file system whose mount point hierarchy includes other mount points.
• A file system that is being used by a process
4-4-3 Restrictions on Creating a File System and Device File
To unify interfaces for creating a file system or a device file, Provisioning Manager changes the following
command utility parameters from the default settings. When manually changing a value, follow the input format
appropriate for each OS.
Restrictions on creating a file system
• Size of a physical partition is specified so that a file system with the maximum size (128 GB (see Note 1)
designated by Provisioning Manager can be created on a single disk.
To specify manually, use the -s option of the mkvg command.
Setting value: 128 MB
Default value: automatically specified 4 MB for AIX ® 5.1, as a value from 1 to 1,024 MB for AIX ® 5.2, and
as a value from 1 to 131,072 MB for AIX ® 5.3 (see Note 1 and Note 2).
NOTE:
• 1: The actual size is smaller than 128 GB. The maximum size of a file system or a device file to be created on a single
disk (LU) is as follows: 128 MB x 1,016 (the maximum number of physical partitions within a single disk) = 127 GB.
When you want to add or expand a disk whose size exceeds 127 GB, use the -t option of the chdev command to
change the maximum number of physical partitions for the corresponding volume group. Note, however, that the
higher the maximum number of physical partitions, the fewer the number of times the disk can be expanded. For
details, see the relevant OS and command reference documentation.
• 2: Minimum possible size for the physical partition is specified so that the specified physical partition size x 1,016 (the
maximum number of the physical partitions within a single disk) can cover the disk space. In the RAID system, a disk
corresponds to an LU that is recognized as /dev/hdiskN rather than to a physical disk.
• The maximum number of physical partitions to be allocated to a logical volume is specified so that a file
system with the maximum size (128 GB
# ) designated by Provisioning Manager can be created.
To specify manually, use the -x option of the mklv command.
Setting value: 1,024
Default value: 512
# 128 GB / 128 MB (size of a physical partition) = 1,024
• NBPI value (number of bytes per i-node) is specified so that a file system with the maximum size (128
GB) designated by Provisioning Manager can be created
# .
To specify manually, use the -a nbpi option of the crfs command.
Setting value: 8,192 bytes
Default value: 4,096 bytes
#: If the NBPI value is too large, the number of i-nodes decreases resulting in a reduction of the number of files
and directories that can be managed. When the NBPI value is 4,096 bytes, which is the default value, the
maximum size of the file system is 64 GB. When the NBPI value is 8,192 bytes, the maximum size of the file
system is 128 GB.
• Because the maximum size of the file to be created is 2 GB by default, and the size is not changeable
once the file is created, the option to enable use of a larger file is specified at file creation
# .
To specify manually, use the -a bf option of the crfs command.
Setting value: true
Default value: false
#: To create a large (128 KB) disk block, even if there is sufficient disk space for file creation, when a required
number of 32-consecutive disk blocks (4 KB x 32) does not exist, file creation fails. If consecutive disk blocks
do not exist, perform defragmentation (defragfs command) to ensure consecutive disk space.
• The setting is specified so that the file system is checked at startup to make sure that the file system does
not have a problem after the system terminated abnormally
# .
To specify manually, use /etc/filesystems.
Setting value: check=true