Date: Tue, 1 Jul 2014 19:20:42 -0700 From: John-Mark Gurney <jmg@funkthat.com> To: Anton Shterenlikht <mexas@bris.ac.uk> Cc: freebsd-arm@freebsd.org Subject: Re: /tmp, /var/log, /var/tmp as /dev/md - why? Message-ID: <20140702022042.GG45513@funkthat.com> In-Reply-To: <201407011046.s61AkJpj006890@mech-cluster241.men.bris.ac.uk> References: <CADL2u4g65eo=7xxAt9j8JumyWneouhM2MGpcA9kfxJaCFWg95Q@mail.gmail.com> <201407011046.s61AkJpj006890@mech-cluster241.men.bris.ac.uk>
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Anton Shterenlikht wrote this message on Tue, Jul 01, 2014 at 11:46 +0100:
> >From r.c.ladan@gmail.com Tue Jul 1 11:37:35 2014
> >
> >2014-07-01 11:25 GMT+02:00 Anton Shterenlikht <mexas@bris.ac.uk>:
> >
> >> Why is it a good idea to mount /tmp and some var dirs on memory disks:
> >>
> >> root@raspberry-pi:/usr/ports # df -m
> >> Filesystem 1M-blocks Used Avail Capacity Mounted on
> >> /dev/mmcsd0s2a 14694 777 12742 6% /
> >> devfs 0 0 0 100% /dev
> >> /dev/mmcsd0s1 16 3 13 20% /boot/msdos
> >> /dev/md0 28 4 22 16% /tmp
> >> /dev/md1 14 0 12 0% /var/log
> >> /dev/md2 4 0 4 0% /var/tmp
> >> root@raspberry-pi:/usr/ports #
> >>
> >> Is this about speed or power, or maybe space?
> >>
> >> Mostly write tear because you're using an SD card, and it improves speed
> >too.
>
> "write tear"?
> Is this a joke, or some technical term?
> I cannot find what it means.
it is a technical term, though I'd be surprised if any SD card had
an issue w/ that anymore...
write tear is where when writing data, only part of the data gets
written and then you loose power... This is mostly an issue on flash
where you have to erase the data beforey ou can program it... Most
flash now have a layer of indirection so that they copy/write the
data to a new flash block, and then point the block there before
erasing the old data... (kinda like a log FS)...
> I get these messages on the console (well, on hdmi port...):
>
> pid ... (svnlite), uid 0 inumber 13 on /tmp: filesystem full
>
> If I unmount /tmp from md and leave it on sd card,
> then I don't see these anymore. What does this mean?
I means that your /tmp fs is to small, and you should either increase
the size of it, or clean it out...
--
John-Mark Gurney Voice: +1 415 225 5579
"All that I will do, has been done, All that I have, has not."
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