out of space error, metadata, extents, defragment problems

From: Fortugno <fortugno_at_cs.usask.ca>
Date: Wed, 27 Mar 1996 11:16:41 -0600

Hi,
        A detailed description of the problem(s) follows.

Main Problem:
        Receiving out of space messages when there is
plenty of space available. Users are unable to save their
work and often lose files whenever this occurs.
  
-Error Message: (file: kern.log)
  Mar 26 13:21:46 xxx vmunix: /student: write failed, file system is full
  Mar 26 13:24:53 xxx last message repeated 10 times

-Space Available:
  Filesystem 1024-blocks Used Avail Capacity Mounted on
  users#student 5493744 2136894 456584 82% /student

        /student is one of seven filesets in the users domain all within
        a single volume. Quotas are in effect for two of the filesets
        including /student.

System:
        DEC Alpha 2100 AXP server running Digital Unix 3.2C

History:
        Having scanned manuals and man pages it was determined that
the problem was related to Metadata table space (extents). Further
reading and scanning of the osf_managers list pointed to running the
defragment utility to help clean things up by first reducing the number
of extents and secondly allowing for enough contiguous space to permit
the extent table to grow, thus eliminating the erroneous out of
space messages. Here is what defragment looked like initally:

 OUTPUT:
 defragment: Gathering data for domain 'users'

 /student: write failed, user disk quota exceeded too long
  Current domain data:
    Extents: 256174
    Files w/extents: 60785
    Avg exts per file w/exts: 4.21
    Aggregate I/O perf: 43%
    Free space fragments: 26382
                     <100K <1M <10M >10M
      Free space: 97% 3% 0% 0%
      Fragments: 26318 64 0 0

        After running defragment during successive evenings the
results revealed a significant improvement and it appeared that the out
of space problem had stopped:

 OUTPUT:
 defragment: Gathering data for domain 'users'
  Current domain data:
    Extents: 86946
    Files w/extents: 61649
    Avg exts per file w/exts: 1.41
    Aggregate I/O perf: 87%
    Free space fragments: 11561
                     <100K <1M <10M >10M
      Free space: 57% 34% 9% 0%
      Fragments: 10862 679 20 0

Additional Problem:
        Then for no apparent reason the out of space messages
began to re-occur and then it was discovered that the defragment
utility no longer would run due to an error which I am unable to track
down any information on:

 OUTPUT:
 defragment: Defragmenting domain 'users'

 Pass 1; Clearing
   Volume 1: area at block 2357584 ( 34928 blocks): 64% full
 defragment: Can't move file /student/xxxxxx/filename.ext
 defragment: Error = ENO_MORE_MCELLS (-1055)
 defragment: Can't defragment domain 'users'

        If someone could help explain why the out of space
messages continue and why defragment keeps failing and if the
two are related and what the solutions to these problems are
that would be appreciated.

Thank You,
Jim

--
Fortugno, V.M.         			fortugno_at_cs.usask.ca
University of Saskatchewan
Received on Wed Mar 27 1996 - 18:49:26 NZST

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