The hard disk interfaces
(wren,
#w,
is a SCSI disk;
ata,
#H,
is an IDE or ATA disk)
serve a one-level directory giving access to the
hard disk partitions.
The parameter to
attach
defines the numerical SCSI
target
and logical unit number
or the IDE
drive
number to access.
Both default to zero.
Each partition name is prefixed by
hd
and the numeric drive identifier.
The partition
disk
always exists and covers the entire disk.
The size of each partition as reported by
stat(2)
is the number of bytes
in the partition, so the size of
disk
is the size of the entire disk.
The partition
partition
also always exists; it is the last block on the disk for SCSI, second to last
for IDE.
If it contains valid partition data, those partitions will be visible as well.
Every time the device is bound, the partitions are updated to reflect any changes
in the partition file.
The format of the
partition
file is the string
plan9 partitions
on a line,
followed by partition specifications, one per line, consisting of a name
and textual strings for the block start and limit for each partition on the disk.
The program
prep(8)
writes the
partition
table for the disk; its use is preferred to writing it by hand.