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Date: Wed, 12 Jan 2000 01:32:34 +0300
From: Alexey Zelkin <phantom@cris.net>
To: current@FreeBSD.org, dillon@FreeBSD.org
Subject: vn device strange behaviour
Message-ID: <20000112013234.A28567@scorpion.crimea.ua>
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hi,

I just discovered some strange points about using vn devices (files) as
swap devices.

I have placed below some output gathered with script(1) and now
some comments.

1) I can easy unconfigure vn device which already mounted as swap device
and then remove swapfile without any problems. I not sure about behaviour
of the swapper when it will try to allocate swap from /dev/vn0c.

2) When I am creating small file (about 100k) and try to mount it as swap
device swapinfo(8) output looks broken.

3) I could not mount three and more vn devices as swap devices.

BTW, I also got strange results once (but I could not reporoduce it later):
swapinfo(8) shown that I have three swap devices mounted: /dev/wd0s1b,
/dev/rvn0c and /dev/#46:10. What's that ? I'll try to reproduce it again,
but ...

Comments ?

-------------------------------------------------

1)

# dd if=/dev/zero of=swapfile count=1 bs=50m
1+0 records in
1+0 records out
52428800 bytes transferred in 8.401941 secs (6240082 bytes/sec)
# vnconfig -e /dev/vn0c swapfile swap
# swapon /dev/vn0c
# swapinfo
Device          1K-blocks     Used    Avail Capacity  Type
/dev/wd0s1b         32640     2640    30000     8%    Interleaved
/dev/rvn0c          51072        0    51072     0%    Interleaved
Total               83712     2640    81072     3%
# vnconfig -u /dev/vn0c
# swapinfo
Device          1K-blocks     Used    Avail Capacity  Type
/dev/wd0s1b         32640     2640    30000     8%    Interleaved
/dev/rvn0c          51072        0    51072     0%    Interleaved
Total               83712     2640    81072     3%
# vnconfig -e /dev/vn0c swapfile swap
# swapon /dev/vn0c
swapon: /dev/vn0c: device already in use
# vnconfig -u /dev/vn0c
# rm swapfile
# swapinfo
Device          1K-blocks     Used    Avail Capacity  Type
/dev/wd0s1b         32640     2640    30000     8%    Interleaved
/dev/rvn0c          51072        0    51072     0%    Interleaved
Total               83712     2640    81072     3%
#

2)

# dd if=/dev/zero of=smallswap count=1 bs=100k
1+0 records in
1+0 records out
102400 bytes transferred in 0.003174 secs (32261453 bytes/sec)
# vnconfig -c /dev/vn1c smallswap swap
# swapon /dev/vn1c
# swapinfo
Device          1K-blocks     Used    Avail Capacity  Type
/dev/wd0s1b         32640     2212    30428     7%    Interleaved
/dev/rvn1c            -28      -28        0   100%    Interleaved
Total               83684     2184    81500     3%
#

3)

# swapinfo
Device          1K-blocks     Used    Avail Capacity  Type
/dev/wd0s1b         32640        0    32640     0%    Interleaved
/dev/rvn0c          51072        0    51072     0%    Interleaved
/dev/rvn1c          51072        0    51072     0%    Interleaved
Total              134784        0   134784     0%
# vnconfig -c /dev/vn2c smallswap
# swapon /dev/vn2c
swapon: /dev/vn2c: Invalid argument
#


-- 
/* Alexey Zelkin                       && phantom@cris.net    */
/* Tavric National University          && phantom@crimea.edu  */
/* http://www.ccssu.crimea.ua/~phantom && phantom@FreeBSD.org */


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