FreeBSD & Software RAID

[Steve Bertrand]

Howard Jones wrote:
> Wojciech Puchar wrote:
>> you are right. you can't be happy of warm house without getting really
>> cold some time :)
>>
>> that's why it's excellent that ZFS (and few other things) is included
>> in FreeBSD but it's COMPLETELY optional.
>>
> Well, I switched from the heater that doesn't work and is poorly
> documented (gvinum) to the one that does and  is (zfs, albeit mostly
> documented by Sun), and so far I am warm :-)
> 
> Once I'd increased kmem, at least. I did get a panic before that, but
> now I am shuffling data happily and slightly faster than gvinum did, and
> memory has levelled off at about 160MB for zfs. I'll be keeping my
> previous hardware RAID in one piece for a little while though, I think,
> just in case! (old Adaptec card with a 2TB limit on containers).

I moved my AMANDA tapeless backup system to ZFS well over a year ago.
It's got four 500GB SATA drives.

At first, it would panic frequently sometime during the backup. The
backups peak at ~400Mbps of network traffic. I adopted the following
script to write out the memory usage during the backup, so I could
better tune the system (sorry, I can't recall where I found this code snip):

#!/bin/sh

TEXT=`/sbin/kldstat | /usr/bin/awk 'BEGIN {print "16i 0";} NR>1 \
{print toupper($4) "+"} END {print "p"}' | dc`

DATA=`/usr/bin/vmstat -m | sed -Ee \
'1s/.*/0/;s/.* ([0-9]+)K.*/\1+/;$s/$/1024*p/' | dc`

TOTAL=$((DATA + TEXT))
DATE=`/bin/date | awk '{print $4}'`

/bin/echo $DATE `/bin/echo $TOTAL | \
/usr/bin/awk '{print $1/1048576}'` >> /home/steve/mem.usage

Cronned every minute, I'd end up with a file like this:

19:16:01 500.205
19:17:02 485.699
19:18:01 474.305
19:19:01 473.265
19:20:01 471.874
19:21:02 471.94

...the next day, I'd be able to review this file to see what the memory
 usage was at the time of the panic/reboot.

I found that:

vm.kmem_size="1536M"
vm.kmem_size_max="1536M"

made the system extremely stable, and since then:

amanda# uptime
 9:01AM  up 81 days, 17:06,

I'm about to upgrade the system to -STABLE today...

Steve
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