[Linux-cluster] GFS and GFS2 : two questions: which is bettter; gfs_controld error

Wendy Cheng wcheng at redhat.com
Sat Sep 1 17:38:19 UTC 2007

Ian Brown wrote:

>  - Hello,
>   I had installed RHEL5 on two x86_64 machine on the same LAN; afterwards I
>   had installed the RHEL5 cluster suite packege (cman-2.0.60-1.el5) and
>   openais-0.80.2-1.el5.
>   I had also installed kmod-gfs-0.1.16- and gfs-utils
>and gfs2-utils.
>   I had crated a 2-node cluster and started the cman service OK on both nodes.
>   Now I tried to create a gfs partition with gfs_mkfs (with -p lock_dlm)
>   and mount it, and I got errors when trying to mount it (this errors
>talk about
>   gfs_controld).
You didn't include the error message here ? This could be a known issue 
where gfs kernel module is not loaded by default (due to a RPM 
dependency problem). To check it out: before mounting the gfs partition ...

1) shell> lsmod
This is to check whether gfs (not gfs2) kernel module is loaded. If yes, 
mount the gfs partition, then read the /var/log/messages file and 
cut-and-paste the print-out (a.k.a the gfs_controld error messages) and 
repost here.

2) shell> cd /lib/modules/'your kernel version'/ extra/gfs
Check if gfs.ko is there. If not, you have installation problems.

3)  shell> insmod gfs.ko
This is to manually load gfs kernel module

4) Retry the mount. If still failing, send us the /var/log/messages file.

>   I made a second try with mkfs.gfs2 (also with -p lock_dlm) );
>   this time I **could** mounted the gfs2 partition succesfully.

GFS2 is part of the base kernel, so it doesn't need to worry about RPM 

>   My questions are:
>     - should I be able with this installation to create and mount a gfs
>     partition ? in case this is possible - what can be my mistale ?

See above.

>     - is gfs2 considered safe to work with ? or is it still experimental and
>     not recommended ? which features do I have in GFS2 which I don't have in
>     GFS?
The advantage of GFS2 are (my personal opinion - not necessarily Red 
Hat's) :
1. It is mainstream and will be well maintained and updated; vs. GFS 
starts to enter maintanence mode. We're hoping to phase out GFS as soon 
as GFS2 is proved to be stable.
2.  It preforms better (faster), particularly for smaller file size, but 
not as stable as GFS.

However, there are tools to facilitate people to migrate from GFS to 
GFS2. So if you want stability, GFS is not a bad choice at this moment.

-- Wendy

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