android_storage/DCIM/.thumbnails/.thumbdata3 inconsistent file size [answered]

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android_storage/DCIM/.thumbnails/.thumbdata3 inconsistent file size [answered]

strange

asked 2016-05-06 04:09:16 +0300

This post is a wiki. Anyone with karma >75 is welcome to improve it.

updated 2016-05-07 02:36:32 +0300

SebM
277 ●49 ●66 ●77

Hi,

When "rsyncing" the DCIM directory to my SD card, I noticed the ~/android_storage/DCIM/.thumbnails/.thumbdata3--1967290299 (anormally big) file was being transfered but what I don't understand is this :

$ ls -l android_storage/DCIM/.thumbnails/.thumbdata3--1967290299 
-rw-rw-r-- 1 root nemo 967472298 2016-05-05 19:09 android_storage/DCIM/.thumbnails/.thumbdata3--1967290299
$ stat -c %s android_storage/DCIM/.thumbnails/.thumbdata3--1967290299
967472298
$ du android_storage/DCIM/.thumbnails/.thumbdata3--1967290299 
64K android_storage/DCIM/.thumbnails/.thumbdata3--1967290299

Both ls and stat report the same size, why does du only report 64K for the same file ?

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The question has been closed for the following reason "the question is answered, an answer was accepted" by SebM
close date 2016-05-07 01:46:07.513134

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Maybe gigabyte digit is ignored by shell, because if you divide 967290299 by 1048576 you get 922,48 ~ 923M. Must fix this immedieate.

alloj ( 2016-05-06 14:31:33 +0300 )edit

@alloj This "967290299" number is contained inside the file name.

My question is why does du report a size of 64KiB ?

SebM ( 2016-05-06 14:38:31 +0300 )edit

So real size of file is 923M?

alloj ( 2016-05-06 14:58:12 +0300 )edit

Yes, the real file size is 967472298

$ python -c "print 967472298.0/2**20"
922.653482437

And here is what my Ubuntu sees through sshfs :

$ df -hT ~/jollaNemoHome
Filesystem       Type        Size  Used Avail Use% Mounted on
nemo@jolla-wlan: fuse.sshfs   14G  6,5G  7,0G  49% /home/sebastien/jollaNemoHome
$ du ~/jollaNemoHome/android_storage/DCIM/.thumbnails/.thumbdata3--1967290299 
944800  /home/sebastien/jollaNemoHome/android_storage/DCIM/.thumbnails/.thumbdata3--1967290299

The coreutils on Sailfish OS 2.0 are quite old, that's maybe why their du has this bug, don't you think ?

SebM ( 2016-05-06 15:03:18 +0300 )edit

Maybe gigabyte digit is ignored by shell, because if you divide 967290299 by 1048576 you get 922,48 ~ 923M. Must fix this immedieate.
alloj ( 2016-05-06 14:31:33 +0300 )edit
@alloj This "967290299" number is contained inside the file name.
My question is why does du report a size of 64KiB ?
SebM ( 2016-05-06 14:38:31 +0300 )edit
So real size of file is 923M?
alloj ( 2016-05-06 14:58:12 +0300 )edit
Yes, the real file size is 967472298
$ python -c "print 967472298.0/2**20" 922.653482437
And here is what my Ubuntu sees through sshfs :
$ df -hT ~/jollaNemoHome Filesystem Type Size Used Avail Use% Mounted on nemo@jolla-wlan: fuse.sshfs 14G 6,5G 7,0G 49% /home/sebastien/jollaNemoHome $ du ~/jollaNemoHome/android_storage/DCIM/.thumbnails/.thumbdata3--1967290299 944800 /home/sebastien/jollaNemoHome/android_storage/DCIM/.thumbnails/.thumbdata3--1967290299
The coreutils on Sailfish OS 2.0 are quite old, that's maybe why their du has this bug, don't you think ?
SebM ( 2016-05-06 15:03:18 +0300 )edit

Answer 1

1

answered 2016-05-07 00:38:04 +0300

Self-Perfection

2496 ●37 ●53 ●49

Looks like an ordinary sparse file. du reports "disk usage" in other words this file occupies just 64KiB on disk. Most of it is not allocated and should return zeroes on read attempt. Trivial check: hexdump -C "$FILENAME" | less

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Comments

You are absolutely right :

$ du --help | grep apparent
      --apparent-size   print apparent sizes, rather than disk usage; although
                          the apparent size is usually smaller, it may be
  -b, --bytes           equivalent to `--apparent-size --block-size=1'
$ du -b android_storage/DCIM/.thumbnails/.thumbdata3--1967290299
967472298   android_storage/DCIM/.thumbnails/.thumbdata3--1967290299

Thanks man :)

SebM ( 2016-05-07 01:45:18 +0300 )edit

android_storage/DCIM/.thumbnails/.thumbdata3 inconsistent file size [answered]

The question has been closed for the following reason "the question is answered, an answer was accepted" by SebM
close date 2016-05-07 01:46:07.513134

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android_storage/DCIM/.thumbnails/.thumbdata3 inconsistent file size [answered]

The question has been closed for the following reason "the question is answered, an answer was accepted" by SebM close date 2016-05-07 01:46:07.513134

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The question has been closed for the following reason "the question is answered, an answer was accepted" by SebM
close date 2016-05-07 01:46:07.513134