xref: /plan9/sys/doc/fs/p7 (revision 6aeb1f0c04d990a2469d1ed5385e6b7f18c098d6)
1219b2ee8SDavid du Colombier.SH
2219b2ee8SDavid du ColombierSync Copy and WORM Copy Processes
3219b2ee8SDavid du Colombier.PP
4219b2ee8SDavid du ColombierThe
5219b2ee8SDavid du Colombier.CW scp
6219b2ee8SDavid du Colombierprocess
7219b2ee8SDavid du Colombierwakes up every ten seconds and
8219b2ee8SDavid du Colombierissues writes to blocks in the buffer cache
9219b2ee8SDavid du Colombierthat have been modified.
10219b2ee8SDavid du ColombierThis is done automatically on important
11219b2ee8SDavid du Colombierconsole commands such as
12219b2ee8SDavid du Colombier.CW halt
13219b2ee8SDavid du Colombierand
14219b2ee8SDavid du Colombier.CW dump .
15219b2ee8SDavid du Colombier.PP
16219b2ee8SDavid du ColombierThe
17219b2ee8SDavid du Colombier.CW wcp
18219b2ee8SDavid du Colombierprocess also wakes up every ten seconds
19219b2ee8SDavid du Colombierand tries to copy a
20219b2ee8SDavid du Colombier.CW dump
21219b2ee8SDavid du Colombierblock from the cache to the WORM.
22219b2ee8SDavid du ColombierAs long as there are
23219b2ee8SDavid du Colombier.CW dump
24219b2ee8SDavid du Colombierblocks to copy and there is no competition for
25219b2ee8SDavid du Colombierthe WORM device,
26219b2ee8SDavid du Colombierthe copy will continue at full speed.
27219b2ee8SDavid du ColombierWhenever there is competition for the WORM
28219b2ee8SDavid du Colombieror there are no more blocks to
29219b2ee8SDavid du Colombiercopy,
30219b2ee8SDavid du Colombierthen the process will sleep ten seconds
31219b2ee8SDavid du Colombierbefore looking again.
32219b2ee8SDavid du Colombier.PP
337dd7cddfSDavid du ColombierThe HP WORM jukebox consists of
347dd7cddfSDavid du Colombier238 disks divided into 476 sides
35219b2ee8SDavid du Colombieror platters.
36219b2ee8SDavid du ColombierPlatter 0 is the
37219b2ee8SDavid du Colombier.I A
38219b2ee8SDavid du Colombierside of disk 0.
39219b2ee8SDavid du ColombierPlatter 1 is the
40219b2ee8SDavid du Colombier.I A
41219b2ee8SDavid du Colombierside of the disk 1.
427dd7cddfSDavid du ColombierPlatter 238 is the
43219b2ee8SDavid du Colombier.I B
44219b2ee8SDavid du Colombierside of disk 0.
457dd7cddfSDavid du ColombierOn Emelie,
46219b2ee8SDavid du Colombierthe main file system is configured
477dd7cddfSDavid du Colombieron both sides of the first 237 disks,
48*6aeb1f0cSDavid du Colombierplatters 0\-236 and 238\-474.
49