Recommended minimal amount of free space to keep?

Ivan Baldo ibaldo at
Mon Jun 9 14:14:47 UTC 2014

     Thanks a lot for the information and hints!
     I think some long time ago I have read somewhere that 70% full 
utilization is a good limit but couldn't find it on the net now though, 
thats why I asked here, thanks for confirming that.
     So, is a percentage thing, not a free space absolute value right?
     If we have a 1000G filesystem then we should have at least 300G 
free to avoid fragmentation in the long term? Or for that filesystems we 
could have just 50G free and get away with it long term?
     Maybe these hints could be in the ext4 manpage or maybe in the wiki.
     Again: thanks!!!

El 07/06/14 22:47, Andreas Dilger escribió:
> You will get better long- term performance if you don't fill the
> filesystems more than about 70% full. Above 90% you are permanently
> fragmenting the filesystem (depends on total size and workload also).
> There is the secondary issue that mke2fs can lay out the filesystem
> better if it is done right at the start rather than resize2fs doing it in
> small increments.  I think as long as you are growing each filesystem
> in chunks of, say, 16GB or more the performance should stay reasonable.
> In many cases, you can have a rough guess at how much space you will
> need in the filesystems, so it doesn't make sense to keep huge amounts
> of free space around.
> Cheers, Andreas
>> On Jun 6, 2014, at 17:57, Ivan Baldo <ibaldo at> wrote:
>>     Hello.
>>     So, LVM is cool, having different partitions for different stuff is cool, and of course Ext4 is cool and *reliable*.
>>     So, we create some logical partitions and put ext4 on them, reserving LVM space for growing those partitions or even making new ones later.
>>     The thing is, I would like to keep every filesystem as small as it can be, but without degrading the performance too much.
>>     I guess that having a filesystem 99% full will create too much fragmentation and many other issues, but having them only 30% full seems like a waste.
>>     Currently I try to keep them at 70% full utilization but I have not based that on anything just guess.
>>     So, what % hysteresis do you recommend? For example, when they get 70% full then grow them so that they get 50% full? Other values?
>>     Thanks for the hints!
>>     Good day everyone.

Ivan Baldo - ibaldo at -
 From Montevideo, Uruguay, at the south of South America.
Freelance programmer and GNU/Linux system administrator, hire me!
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