[Fedora] Re: Alternatives to du

[Les Mikesell]

Mark Haney wrote:
>>> tracking a lot of hard links, it might be using a lot of memory -- I'd
>>> think it would have to store the inode number for each multi-linked 
>>> file.
>>> I don't know what it does with hard-linked directories (but don't use
>>> hard-linked directories!).
>>
>> Compare the performance to a "find . -size 1024" >/dev/null
>>
>> The find is fetching as much inode and name space data but shouldn't be
>> doing any link work.
>>
> 
> I just tried this on the same 3TB volume as the du and I get almost 
> identical results, ~90 minutes.

On my 250 gig backuppc partition:

# time du -sh .
189G    .
real    1190m47.881s
user    2m37.849s
sys     23m20.980s

# time find . |wc -l
21120513
real    84m47.798s
user    1m22.193s
sys     9m56.232s

So I think most of the real time is being spent waiting for disk seeks 
to the inodes.  Since most of the filenames are hardlinks to older 
files, none of the tricks normally used to group inodes allocated within 
a directory can work.   Most 'normal' accesses to this partition are 
fast though. In particular it is backing up 20 other machines and 
checking for duplicates of all new files with its scheme of hashing and 
looking for an existing file.  But, the last time I tried to copy one of 
these with tar or dump I gave up when it wasn't finished after 3 days.

-- 
   Les Mikesell
    lesmikesell at gmail.com