From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <181f918ef3641b854a5fcd822a1973e5@gmx.de>
To: 9fans@9fans.net
Date: Fri,  8 May 2009 18:27:28 +0200
From: cinap_lenrek@gmx.de
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Subject: [9fans] cwfs
Topicbox-Message-UUID: f6a3687a-ead4-11e9-9d60-3106f5b1d025

Have converted my fossil/venti filesystem to cwfs (with history) and
made boot code so that i can start off from it. On the way i had to change
cwfs a bit so that it can cope with the long filenames from my mp3
collection and as it was supposed to run on my cpu server, i reduced
the cache memory size to be a quarter of all free userspace memory.

converting fossil to cwfs:

used the cphist program from http://www.quanstro.net/plan9/history.pdf
and wrote a /dev/(bin)time faking fileserver
(/n/sources/contrib/cinap_lenrek/delorean) that fools cwfs and replica
about the current time, but does not confuse cron and fossil.  you
have to manualy convert fossils /adm/users to cwfs format.  the
sequence is this: start cwfs type "allow" and "users default".  then
mount it and copy a users file in the root.  then type "users /users"
and remove the file again before doing the replica.  after replica
copy that file again to /adm/users so that on next startup the owners
and groups get loaded correctly.  for the replica you better make a
script and check the fossil dumps for corrupted directories.  i had
several metadata corruptions in the root direcotiry of fossil dumps
that caused replica to remove anything just to recreate it on the next
round. in the end i made a list of bad dumps that got skpied in
the script. the good news is that you can do all this while your fossil
cpuserver is running so if you find problems you can start over again
and to crazy things while anything is still running.

booting from cwfs:

/n/sources/contrib/cinap_lenrek/local.c (copy to /sys/src/9/boot/local.c)

the important part of the kernel configuration looks like this:

boot cpu boot w0
	tcp
	local

bootdir
	bootpccpuc.out boot
	/386/bin/ip/ipconfig
	/386/bin/auth/factotum
	/386/bin/cwfs

cwfs as the original stand alone fileserver has its own device names. cwfs
needs a device mapping file that maps plan9 files to cwfs devices.
connectlocalcwfs() builds that mapping dynamicly from plan9.ini keys
in the form wN=file. so my plan9.ini looks like this:

bootfile=sdE0!9fat!9pccpuc
bootargs=local!w0
bootdisk=local!w0
w0=#S/sdE1/data

on boot, cwfs is started in config mode so one can recover from errors. after
typing "end" on the cwfscmd promt stdin of cwfs is put in /srv/cwfscmd
and the filesystem gets mounted.

misc:

dont forget to change fshalt to do something like this:

f=...
k=...
c=`{ls /srv/cwfs*cmd >[2]/dev/null}

for (i in $c){
	echo -n $i...
	echo halt >>$i
}

cwfs needs to be halted correctly as it has no jurnaling or softupdates.

--
cinap