[Gluster-users] file open/write/move causing blank content in files

Daryn Hanright daz at planetnz.com
Wed Jun 12 02:24:30 UTC 2013


Have found an issue with our installation of gluster, and need some advice
on how to procede.

I wrote out a bug report detailing the issue.


I'm not sure if its a gluster configuration problem, or an actual bug. Or
even a VM thing. Or combination of both.

Will briefly describe the issue I am seeing (bug report above more

In an application I'm developing on a 2 brick gluster installation (2
Centos 6 VM's), occasionally I'd see a file that appeared to exist in both.

The permissions on both files exactly the same. Also the timestamp. I would
however notice in the application logs a few "permission denied" errors
occuring, I'm assuming because my application is trying to read a file
thats currently being written.

This is the strange bit. When I cat/less the file, on 1 server its blank.
On the other the content of the file is fine. If I 'touch' the blank file
the content of the file comes back.

So I wrote a couple of quick & dirty PHP scripts effectively duplicating
what the application tries todo.

write.php - this basically opens and write a file to a directory (in a loop
- 100 files). I read its contents in. I then move the file to another
gluster directory.
read.php -  finds files in both directories & tries to read contents in. In
a loop with no time delay in reading

Every single time, I end up with at least 1 file (mostly more than 1) which
has the characteristics I've described in both the original directory, and
the directory where the file was moved. Indicating that either a
file->open->write or a file->mv AND reading the files at the same time
causes it.

It would be nice if I could figure out what might be happening here. Is it
a bug? Maybe a config issue?

# gluster volume info

Volume Name: prxvol
Type: Replicate
Volume ID: b5879503-3c6b-4556-b6ee-e600208150a7
Status: Started
Number of Bricks: 1 x 2 = 2
Transport-type: tcp
Options Reconfigured:
diagnostics.brick-log-level: INFO
diagnostics.client-log-level: INFO
cluster.data-self-heal-algorithm: diff

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