[mythtv-users] sluggish system, potential HD failure, and how best to get back up and runnin

Hika van den Hoven hikavdh at gmail.com
Thu Mar 6 13:14:43 UTC 2014

Hoi Simon,

Thursday, March 6, 2014, 12:06:35 PM, you wrote:

> Hika van den Hoven <hikavdh at gmail.com> wrote:

>> Note the difference between ramfs
>> and tmpfs. ramfs assigns space at need and tmpfs assigns an in kernel
>> predefined size. A size you can change with kernel options.

> As I read things, that's not correct.
> ramfs doesn't limit the size - so you can keep writing until memory
> is all used up and OOM killer will crash the system. tmpfs has a
> fixed upper size which you can set at mount time.
> I'm pretty certain that neither allocates the memory until it is
> actually used. I have a system (sort of semi-embedded and running
> from a CF card) where I've put several volatile filesystems on tmpfs
> - and until I realised the presence of the size option, I had the
> tmpfs volumes adding up to twice the available ram (and no swap on the system).

> https://wiki.debian.org/ramfs

> https://www.kernel.org/doc/Documentation/filesystems/tmpfs.txt
>> tmpfs puts everything into the kernel internal caches and grows and
>> shrinks to accommodate the files it contains ...

> http://www.thegeekstuff.com/2008/11/overview-of-ramfs-and-tmpfs-on-linux/

> _______________________________________________
> mythtv-users mailing list
> mythtv-users at mythtv.org
> http://www.mythtv.org/mailman/listinfo/mythtv-users
> http://wiki.mythtv.org/Mailing_List_etiquette
> MythTV Forums: https://forum.mythtv.org

I might have misinterpreted the preallocation part. But the default
size for tmpfs is quite small. I believe 8 Mb. If you set it higher
with ramdisk_size=xxx (in kb) it goes for all tmpfses.
If you use ramfs you have to be aware of its maximum size to prevent
swapping. Therefore I say only use it for /tmp and not for /var/tmp.

Tot mails,
  Hika                            mailto:hikavdh at gmail.com

"Zonder hoop kun je niet leven
Zonder leven is er geen hoop
Het eeuwige dilemma
Zeker als je hoop moet vernietigen om te kunnen overleven!"

De lerende Mens

More information about the mythtv-users mailing list