ITEM: W5089L

v3fshelper errors on chfs when filesystem is 100% full



AIX 3.2.5


Customer has a filesystem that "df" says has 57344 Total Kb.  It 
is currently 100% full.  When he tries to increase it, he gets 
the following error:

  v3fshelper: /dev/lv03: No space left on device
  v3fshelper: delete a file and try again

After moving a single file to another location, the customer was
able to increase the filesystem.  However, usually when 100% full,
filesystems can normally be easily increased.


There is one map page allocated per every 56Mb of filesystem
space (57344Kb).  When the map is full, "chfs" will fail with
the above error messages since there is no space in the map
pages to increase the filesystem.

This was a known problem at AIX 3.2.5 that was fixed in version 4.1,
where the algorithm for increasing the size was changed.  Here is 
a description of the problem:

This condition occurs when the diskmaps are full and there is not
enough free space to extend the maps to their new size. In AIX 3.2,
one map page always covered 56M of disk. Thus, this condition
occured on 56MB boundies. On AIX 4.1 the boundry conditions are
as follows:

  Frag Size --> 1 map mage describes
  512           8M
  1024          16M
  2048          32MB

In this case the extension is going from 16M to 32M; this requires 2
new map pages and one indirect block.

As stated, the algorithm has been changed.  Testing this scenario
with a 112Mb filesystem with a default fragment size of 4096
bytes, and with the fragment sizes and filesystem sizes given
above, and the problem has indeed been fixed at version 4.1.x.

There are no plans to correct this situation in AIX 3.2.5.  The
workaournd is to make sure that there is 8k available in the file
system in order to increase it.

Next:   Close.

Support Line: v3fshelper errors on chfs when filesystem is 100% full ITEM: W5089L
Dated: August 1995 Category: N/A
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