HP JFS 3.3 and HP OnLineJFS 3.3 VERITAS File System 3.3 System Administrator's Guide

44 Chapter2
Disk Layout
Disk Space Allocation
Disk Space Allocation
Disk space is allocated by the system in 1024-byte sectors. An integral
number of sectors are grouped together to form a logical block. VxFS
supports logical block sizes of 1024, 2048, 4096, and 8192 bytes. The
default block size is 1024 bytes for file systems less than 3 gigabytes;
2048 bytes for file systems less than 16 gigabytes; 4096 bytes for file
systems less than 32 gigabytes; and 8192 bytes for file systems 32
gigabytes or larger. The block size may be specified as an argument to
the mkfs utility and may vary between VxFS file systems mounted on
the same system. VxFS allocates disk space to files in extents. An extent
is a set of contiguous blocks.