ADSM-L

Linux Sparse Files

2006-10-03 10:12:10
Subject: Linux Sparse Files
From: "Robinson, Brian D." <brian.robinson AT NSCORP DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Tue, 3 Oct 2006 10:03:30 -0400
We are running AIX 5.2.0, TSM 5.2.6 server, with a TSM Client 5.3.4 running
on Red Hat version 4.

We seem to be having an issue with Linux sparse files - see description
below.  The manual says that TSM will process sparse files - but that is
about it. When the backup hits this file it seems to go OK until it actually
hits the actual file size(168K) then it shows it was unsuccessful, but still
waits on a media mount.  Has anyone else come across this?

Brian Robinson
-----------------------------------------------------------
168K -r--------  1 root root 1.2T Oct  3 09:37 lastlog


This is from the Red Hat Knowledge Base...

----------------------------------------------------
Issue:
Why is the /var/log/lastlog file so large?

Resolution:

The size of the file /var/log/lastlog can appear to be overly large on some
systems, most especially in 64 bit architectures.

ls -la /var/log/lastlog
-r--------    1 root     root     1254130450140 Jul 27 08:25
/var/log/lastlog

>From the above example, the lastlog file is reporting to be ~1.2TB in size.
This file is large since it contains information regarding the last login
for all users. The UID of nfsnobody on 64 bit systems is 4294967294 or 2^32
- 2, this is considered to be the last UID on the system. Some arithmetic to
show how the 1TB size is reached can be found below:

4294967294 * 256 = 1099511627264 bytes

>From the calculation we see above, 256 is the amount of space each UID entry
takes up in the lastlog file.

This file is what we call a sparse file. A man page for each of those
commands for further information.

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http://kbase.redhat.com/faq
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