xref: /plan9-contrib/sys/doc/fs/p7 (revision 219b2ee8daee37f4aad58d63f21287faa8e4ffdc)
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 Sony WORM jukebox consists of
3450 disks divided into 100 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 50 is the
43.I B
44side of disk 0.
45On Bootes,
46the main file system is configured
47on both sides of the first 45 disks,
48platters 0-44 and 50-94.
49Slots 46-49 are available for mounting
50blank disks for making backup copies of platters.
51To back up the logical 57th platter in the file system, which is physical platter 62,
52insert the blank platter in the input
53carrier and type
54.P1
55    wormingest 49
56    wormcp 62 49
57.P2
58To have the backup disk have the
59correct platters on its two sides,
60the blank platter inserted should be the
61.I B
62side up of the disk containing the
63backup of logical (and physical) platter 12.
64When the copy is done, type
65.P1
66    wormeject 49
67.P2
68