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Re: disk usage monitor figures don't add up?



On Thursday 09 December 2004 08:32, Jeff Vian wrote:
>On Thu, 2004-12-09 at 03:42 -0500, Gene Heskett wrote:
>> Greetings;
>>
>> I need a bit of help from the ext3 filesystem folks I think.   I'm
>> haveing a comprehension problem here.  A snip from a df report:
>>
>> /dev/hdd3      176100712   165509176   26340  100.3% /amandatapes
>>
>> >From the above, there is about 10GB on the missing list!  Amanda
>> > just
>>
>> bailed out early because the disk was full, while the 2 figures on
>> the left claimed there should have been somewhere between 10GB and
>> 11GB of space left, not the 26 megs shown above.
>>
>> The output of a du . on that partition, before I ran the amflush,
>> was 165509176 bytes total used out of 176100712 that df claimed it
>> has for a total, both in 1024 byte kilobytes.
>>
>> So my question is: Where is the math broken?  Both du and df, or
>> my head?
>>
>> Surely there cannot be 10+GB tied up in inodes and journals?
>
>Math is not broken.  The system automatically reserves a portion of
> the partition that is usable only by root, and any user space
> application will see the partition as 100% when it reaches this
> level. Without this reserved space, when a partition becomes 100%
> full it would not even accessible by root and thus the partition
> data could be lost completely.
>
>IIRC the number used to be 10% reserved, 90% user back when drives
> were a lot smaller. That may have changed but I do not know the
> actual number now.
>
>The available above and the difference in numbers indicate it still
>might be the original 10% reserved space that got you.

Ahh, I wasn't aware of that distinction.  Thank you.

In this case its a huge gotcha of over 10GB.   Thats more like 13%. 
Is there any way to reduce this to a fixed figure of say 500 megs or
so since amanda doesn't run as root, but suid root for much of what it
does? 

Or is it time to revisit the srcs for du & df & add a _max_reserved?

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
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by Gene Heskett are:
Copyright 2004 by Maurice Eugene Heskett, all rights reserved.



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