Ocfs2 users - Mar 2010 - log files appended with NULL when node lost power

A and B are identical machines. Network has lots of redundancy. They
both access same OCFS2 volumes over Fiber Channel on a SAN.

Red Hat Enterprise Linux Server release 5.3 (Tikanga)
2.6.18-128.el5 x86_64
OCFS2 1.2.9

There's a software appending lines to some log files on a SAN volume 
shared by both nodes. Either system can write to the log files.

As a redundancy test, I cut off power to node A while doing transactions 
on the site (sudden cut-off, no graceful shutdown). While logged in to 
node B, I noticed some log files appeared to be filled with NULL (00 
hex) characters at the end.

When I powered node A back on, the log files turned normal all of a 
sudden. Looks like no logging data was lost, I could read the lines that 
were logged while A was down.

It's just during the power shutdown on node A, the files appeared padded 
with NULL at the end on node B, but turned back normal when A came back 
online.

Is this something that can be fixed?

-- 
Florin Andrei
http://florin.myip.org/

What you are seeing is the result of writeback data journaling
in ocfs2 1.2. In ocfs2 1.4, we default to ordered data journaling.
Refer to the 1.4 user's guide for more.

Florin Andrei wrote:
> A and B are identical machines. Network has lots of redundancy. They
> both access same OCFS2 volumes over Fiber Channel on a SAN.
>
> Red Hat Enterprise Linux Server release 5.3 (Tikanga)
> 2.6.18-128.el5 x86_64
> OCFS2 1.2.9
>
> There's a software appending lines to some log files on a SAN volume 
> shared by both nodes. Either system can write to the log files.
>
> As a redundancy test, I cut off power to node A while doing transactions 
> on the site (sudden cut-off, no graceful shutdown). While logged in to 
> node B, I noticed some log files appeared to be filled with NULL (00 
> hex) characters at the end.
>
> When I powered node A back on, the log files turned normal all of a 
> sudden. Looks like no logging data was lost, I could read the lines that 
> were logged while A was down.
>
> It's just during the power shutdown on node A, the files appeared
padded
> with NULL at the end on node B, but turned back normal when A came back 
> online.
>
> Is this something that can be fixed?
>
>