Re: filesystem and `softdep'

["Marco Peereboom" <slash@peereboom.us>]

It's a laptop right? That means it has a built in UPS so turn it on :-)
And next reboot (or remount) comes around and writes are significantly
faster!

The first question should always be: is the data that I potentially can
loose worth the speed increase. Common sense is the only right way to
determine which slices you'll need it on. For example, don't turn it on
for slices that contain mostly binaries (/, /usr etc) and turn it on for
regularly changing slices (like /tmp, /var etc).

I use it all over the place because the performance increase is usually
worth it. On my critical boxes I usually don't but when I do I have them
on a UPS.

Example my web & mail server (on UPS):
/dev/sd0a / ffs rw 1 1
/dev/sd1a /home ffs rw,softdep,nodev,nosuid 1 2
/dev/sd0d /tmp ffs rw,softdep,nodev,nosuid 1 2
/dev/sd0e /usr ffs rw,nodev 1 2
/dev/sd1b /var ffs rw,softdep,nodev,nosuid 1 2

Example my toy dev box (on UPS):
/dev/sd0a / ffs rw,softdep 1 1
/dev/sd0f /mnt/junk ffs rw,softdep,nodev,nosuid 1 2
/dev/sd0e /tmp ffs rw,softdep,nodev,nosuid 1 2
/dev/sd0g /usr ffs rw,softdep,nodev 1 2
/dev/sd0h /usr/src ffs rw,softdep,nodev,nosuid 1 2
/dev/sd0d /var ffs rw,softdep,nodev,nosuid 1 2

> -----Original Message-----
> From: owner-misc@openbsd.org [mailto:owner-misc@openbsd.org] 
> On Behalf Of Harry Putnam
> Sent: Thursday, May 01, 2003 22:43
> To: misc@openbsd.org
> Subject: filesystem and `softdep'
> 
> 
> NEW TO OBSD ALERT 
> Running (3.2)
> 
> Following threads here a ways back, a big one about setting 
> up disks and slices etc.  Early March, Subject: fdisk = fsck! 
> I noticed in several posted `mount' readouts that those 
> posters have `softdeps' as a flag on many slices.
> 
> Checking the mount man page it appears softdep is a 
> desireable flag and may enhance speed of read write 
> operations.  (I'm running an older TOSHIBA laptop with 96mb 
> RAM [low by current standards])
> 
> I wondered if adding this option is as simple as editing 
> /etc/fstab and they will be in force on next reboot?  Are 
> there any downsides to using softdeps.  Any slices that 
> should avoid them?
> 
> Also, I wondered if the flag can be set without a reboot?  
> Maybe umount and remount using the -o switch to mount.
> 
> I used something close to default slicing taken from install 
> instruc- tions but wondered if I might be getting in over my 
> `NEW TO OBSD' head by adding that flag to these slices:
> 
> /dev/wd0a on / type ffs (local)
> /dev/wd0g on /home type ffs (local, nodev, nosuid)
> /dev/wd0d on /tmp type ffs (local, nodev, nosuid)
> /dev/wd0f on /usr type ffs (local, nodev)
> /dev/wd0e on /var type ffs (local, nodev, nosuid)
> 
> Specifically, the mount man page mentions a kernel option 
> FFS_SOFTUPDATES... is that built in to stock 3.2 kernel?