MyCloud allocation unit 1MB

Legacy Products My Cloud OS 3
1

I noticed a big difference between “size” and “size on disk” on my new 3TB NAS. A small test revealed the the allocation unit size is 1MB instead of the default 4KB of NTFS (meaning that a 1KB file takes 1MB of disk space, or, a 1.01MB file takes 2MB of disk space). This very much explains why a 191GB size backup takes 225GB disk space (34GB waste !).

Why would WD pre-format the disk with such a big allocation unit and how can I change it?

2

How did you determine that?  Mine is set with 4k block size.

3

My system also has 4K blocks.  Secondly a 191G file should at most be at most 1MB bigger.

Use the following tune2fs -l /dev/sda4.  It will show the block size.

RAC

4

By saving a 800 byte text file and checking its properties. The same file on the local disk shows as 4k (Size on disk).

AllocationUnit.jpg
AllocationUnit.jpg1152×648 48.5 KB

5

By 191GB I meant ~ 40K files in a backup, not just a single file. Sorry for the confusion.

6

This appears to be a bug in windows.  I have a file on MY Cloud it is 787 bytes.  Windows properties says it is

787 bytes 1MB on disk.  If I ssh into MY Cloud and do a stat .bashrc is displays the following:

 stat .bashrc
  File: `.bashrc’
  Size: 787             Blocks: 8          IO Block: 4096   regular file
Device: 804h/2052d      Inode: 88612774    Links: 1
Access: (0755/-rwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2015-02-26 16:19:02.522950002 -0500
Modify: 2015-02-27 19:09:45.381154000 -0500
Change: 2015-02-27 19:09:45.391154000 -0500
 Birth: -

RAC

7

Thanks RAC. I know nothing about ssh, but interesting result. I have another device on my network (a streamer with its own disk) and I realized, just now, that the same problem exists there too. So it’s either a Windows problem or a problem in the way non Windows devices report back to Windows (the problem does not exist on Windows machines or external disks directly attached to Windows machines). 

Thanks,

Moty

8

Not a windows bug.  Read up on what’s called the Samba allocation roundup size.