xref: /plan9/sys/doc/fs/p7 (revision 6aeb1f0c04d990a2469d1ed5385e6b7f18c098d6)
1.SH
2Sync Copy and WORM Copy Processes
3.PP
4The
5.CW scp
6process
7wakes up every ten seconds and
8issues writes to blocks in the buffer cache
9that have been modified.
10This is done automatically on important
11console commands such as
12.CW halt
13and
14.CW dump .
15.PP
16The
17.CW wcp
18process also wakes up every ten seconds
19and tries to copy a
20.CW dump
21block from the cache to the WORM.
22As long as there are
23.CW dump
24blocks to copy and there is no competition for
25the WORM device,
26the copy will continue at full speed.
27Whenever there is competition for the WORM
28or there are no more blocks to
29copy,
30then the process will sleep ten seconds
31before looking again.
32.PP
33The HP WORM jukebox consists of
34238 disks divided into 476 sides
35or platters.
36Platter 0 is the
37.I A
38side of disk 0.
39Platter 1 is the
40.I A
41side of the disk 1.
42Platter 238 is the
43.I B
44side of disk 0.
45On Emelie,
46the main file system is configured
47on both sides of the first 237 disks,
48platters 0\-236 and 238\-474.
49