Migration from CentOS 5.6 to Scientific Linux 6.1

Submitted by helpmin on Sat, 08/13/2011 - 08:18

I migrated from CentOS 5.6 to Scientific Linux (may be a bit risky, but did it anyway). Works great so far.

Noticed a few minor issues when I restored my virtualmin domains. But otherwise worked great. Enjoying SNI without mod_gnut tls now :-)

  • Bind didn't work and needed a few adjustments, like rndc, remove allow-query and a couple of other small things (basically compared old and new config and fixed settings).
  • System logs module in webmin doesn't work
  • Deleting an Alias Domain did not remove the corresponding zone entry

I also see the following Postfix warnig messages now:

doveconf: Warning: Obsolete setting in /etc/dovecot/dovecot.conf:21: protocols=imaps is no longer necessary, remove it
doveconf: Warning: Obsolete setting in /etc/dovecot/dovecot.conf:21: protocols=pop3s is no longer necessary, remove it
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Comments

Submitted by JamieCameron on Sat, 08/13/2011 - 11:10

How did you do this migration exactly - was it an upgrade of the system, or did you backup all domains, reinstall the new os and then restore?

Joe's picture
Submitted by Joe on Sat, 08/13/2011 - 13:18 Pro Licensee

The System Logs module is related to the move to rsyslog instead of ksyslogd in RHEL/CentOS/SL version 6. This is incompatible with either of the syslog daemons Webmin's System Logs module supports at this time (which is syslog and syslog-ng)...though the actual logs are the same, and so Jamie can probably fix the log viewing in the next release; I'm not sure how long it will take to get the configuration file supported.

Jamie, http://www.rsyslog.com/ is the website of the new syslog in RHEL/CentOS/SL 6. Looks like a crazily complex configuration file, as it is a programming language for defining logging behavior, rather than a declarative language for specifying log locations and such. So, it seems really powerful, but also difficult to put a UI on top of.

Submitted by helpmin on Sat, 08/13/2011 - 16:32

Jamie Correct, backup and then restore. Redhat doesn't support upgrades between major releases unfortunately.

Submitted by JamieCameron on Sat, 08/13/2011 - 17:32

The syslog issue is a Webmin OS detection bug .. on CentOS 6, it should be looking at /etc/rsyslog.conf which has mainly the same format at classic syslog. I will fix this in the next Webmin release .. or you can go to Webmin -> Un-used Modules -> System Logs -> Module Config, and change the config file path to /etc/rsyslog.conf .

Submitted by helpmin on Sat, 08/13/2011 - 19:55

That works.

Another odd thing I noticed on SL 6.1.

I see the following error messages in the log. Used to work on CentOS 5.6 (with bleeding repo)

mod_fcgid: HTTP request length 138557 (so far) exceeds MaxRequestLen (131072)

Submitted by helpmin on Sat, 08/13/2011 - 20:00

Here is probably the explanation:

Before 2.3.6, this defaulted to 1GB. Most users of earlier versions should use this directive to set a more reasonable limit.

Submitted by JamieCameron on Sat, 08/13/2011 - 23:59

Yes, that's the reason .. annoyingly, in mod_fcgid 2.3.6 and later they made the max request length settable, but changed the default to 1GB, which I think was a poor design. Virtualmin tries to fix this by setting "FcgidMaxRequestLen, but the code to determine if this directive is available differs on a distro by distro basis .. and doesn't support CentOS 6 yet. I will fix that in the next Virtualmin release.

Submitted by helpmin on Sun, 08/14/2011 - 05:23

Sounds good. Thanks.

Were you able to reproduce some of the BIND issues? I did the migration on a live site, and had to try to find a quick fix asap (quite risky, but I have a lot of faith in you guys :-). Unfortunately during this hectic process I didn't think of writing down everything for you guys. So a lot of details got lost.

Submitted by JamieCameron on Sun, 08/14/2011 - 14:40

No, BIND worked fine for me .. could you tell us more about what fixes you had to make?

Submitted by helpmin on Mon, 08/15/2011 - 00:10

As mentioned already I did not think of writing down all the exact details :-)

But at a minimum I had to click run setup rndc (because apply zone didn't work) and in the end I had to remove comment out allow-query { address_match_list };.

Settings forAllow recursive queries from was also different. That's all I remember.

Submitted by JamieCameron on Sun, 08/14/2011 - 23:03

Odd, perhaps these are specific to Scientific Linux 6, because I don't see them after doing a fresh install on CentOS 6?

Submitted by helpmin on Mon, 08/15/2011 - 00:09

Correct, on a fresh install you won't see the error. I saw them when I restored virtual servers from 5.6 to 6.

I don't think it is a difference between SL and C (they are identical except for a one or two additional packages, which are not installed)

May be a difference between 6.0 and 6.1. Did you test 6.1?

Submitted by helpmin on Mon, 08/15/2011 - 05:18

Actually forget the SL 6.1 part. I tested SL 6.0 :-)

I am just so used after "yum update -y" that the system should be on the latest version. Not so on SL6 :-)

Submitted by JamieCameron on Mon, 08/15/2011 - 14:01

Ok, I see the cause of this now .. the default BIND config on CentOS 6 is really stupid, as it disallows queries from anything other than localhost. I'll update our installer to fix that..

Submitted by helpmin on Mon, 08/15/2011 - 16:45

Ok, great. Would you be so kind to post your "new" default BIND configuration here? I would like to compare.

And what about the "setup rndc necessary" issue. You were not able to reproduce that one?

Submitted by JamieCameron on Mon, 08/15/2011 - 19:15

I couldn't re-produce the rndc issue .. it was setup just fine for me.

As for the issue of BIND not answering queries, my fix was to edit /etc/named.conf and remove the line :

allow-query     { localhost; };

and change the lines :

listen-on port 53 { 127.0.0.1; };
listen-on-v6 port 53 { ::1; };

to :

listen-on port 53 { any; };
listen-on-v6 port 53 { any; };