The number of blocks reserved for root should be reconsidered

[Vesa Paatero]

Thanks, Bear. I think, though, that when you are running out of disk 
space, performance becomes secondary as the priority shifts towards 
getting as much space as you can.

So, when you don't have space you prefer a low reservation level and 
when you do have abundant space, the reservation level doesn't matter. 
That's why I would set the reservation at a level where the necessary 
system processes are allowed to function with sufficient space but not 
much above that.

Vesa


17.10.2011 22:52, Bear Giles wrote:
>
> A major reason for that space is liquidity, for lack of a better 
> phrase. If you have 5% reserved you can probably allocate a new block 
> near your existing file. If you only have, say, 1%, you will probably 
> have a lot more thrashing.
>
> However this all assumes the same file size distribution as in the 
> past. It may be better, or it may be worst, with gigabyte media files. 
> Shudder. Imagine the thrashing with a poorly distributed video file.
>
> On Oct 17, 2011 11:45 AM, "Vesa Paatero" <vpaatero at lavabit.com 
> <mailto:vpaatero at lavabit.com>> wrote:
>
>     Hello,
>
>     When Ubuntu installers create disk partitions, they reserve the
>     default 5% of blocks for root-only use. For nowadays hard disks,
>     however, that percentage can make dozens of gigabytes, which seems
>     much more than the necessary/reasonable amount for that purpose.
>
>     People can change the reserved size afterwards by using tune2fs if
>     they know that such a reservation takes place... but since Ubuntu
>     is aiming to be easy-to-use distro, particularly suited for those
>     who don't know the stuff "under the hood", it would be best if the
>     installer set the optimal size of the root-only reservation
>     automatically.
>
>     So, how about if some people with a good idea of the disk usage of
>     the basic system services decide what the right amount to be
>     reserved (as a function of disk space?) is and then someone who
>     knows the installation scripts could make the necessary changes there?
>
>     Should I add an entry about this into some database.. the bug
>     database, the brainstorm system or what others there are?
>
>     Thanks for considering it,
>     Vesa
>
>
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