From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Thu, 11 Aug 2011 10:11:27 +0200
From: David du Colombier <0intro@gmail.com>
To: 9fans@9fans.net
Message-ID: <20110811101127.52627669@wks-ddc.exosec.local>
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Subject: Re: [9fans] Fossil fs recovery
Topicbox-Message-UUID: 0e43a4fc-ead7-11e9-9d60-3106f5b1d025

In fact, it's pretty straightforward.

In the following example, I consider you have a disk sdE0
with Fossil, and you want to add a disk sdE1 with Venti.

Create the Venti partitions:

disk/fdisk -baw /dev/sdE1/data
disk/prep -bw -a^(isect arenas bloom) /dev/sdE1/plan9

Format the Venti file systems:

venti/fmtisect isect /dev/sdE1/isect
venti/fmtarenas arenas /dev/sdE1/arenas
venti/fmtbloom /dev/sdE1/bloom

Since the bloom filter requires memory equal to its size
on disk, you could need to pass the parameter -s to fmtbloom
to specify its size or directly adjust the partition size.
Keep in mind that Venti use 20% total memory by default, and
1/3 of it is allocated to the bloom filter.
For example, with 1 GB of memory, you cannot have a bloom filter
larger than 64 MB (which is sufficient) with the default settings.
Of course, the bloom filter is optional anyway.

Configure Venti:

echo 'index main
isect /dev/sdE1/isect
arenas /dev/sdE1/arenas
bloom /dev/sdE1/bloom' | venti/conf -w /dev/sdE1/arenas

Initialize the index sections:

venti/fmtindex /dev/sdE1/arenas

Read your current Fossil configuration:

fossil/conf /dev/sdE0/fossil > fossil.conf

Edit fossil.conf, it should look like something like:

fsys main config /dev/sdE0/fossil
fsys main open -V -c 3000

Remove -V to open and srv if needed, then
add the following line to enable automatic
snapshots:

fsys main snaptime -s 60 -a 0530 -t 2880

(snapshot at 05:30, temporary snapshot each
 hour and discarded after two days)

Write your new Fossil configuration:

fossil/conf -w /dev/sdE0/fossil < fossil.conf

Mount your 9fat file system, then add the following line
to the file /n/9fat/plan9.ini:

venti=#S/sdE1/arenas

After rebooting, the current Fossil content will be dumped
to Venti.

--
David du Colombier