Hi all,
We've recently updated the storage at Edinburgh to be dual stacked
IPv4/v6.
Unfortunately we hit a few problems which may be site specific but I
don't know if anyone else has experienced these issues and knows any
potentially good/better fixes.
Unfortunately all of the boxes we've updated are running
ScientificLinux6. I'm keen to migrate these to CentOS7 but this is less
of a priority to enabling IPv6 support.
1)
The first issue is that our IPv6 storage nodes were untrusted by DPM
after updating to the latest (non-DOME) builds. This was solved by
explicitly adding the IPv6 addresses into the shift.conf files. (After
the IPv6 address for all hosts had been registered all machines were
restarted).
The reverse DNS appears to be working for all of the machines and the
gai.conf file which has been shared around for configuring getaddrinfo
resolution was present on all machines. I don't know if this could just
have been a DNS caching issue for the first 24/hr but I plan not to
investigate too much further.
2)
MySQL 5.1 . This is the default version of Mysql on ScientificLinux6
which doesn't have complete IPv6 support according to some
documentation.
(Our DB is hosted on the same machine as the DPM head node and is not
externally accessible).
MySQL 5.1 struggled struggled to connect for our IPv6 https DPM
connections. This was tracked down to MySQL 5.1 not binding to an IPv6
port. (When forced to bind to an IPv6 address in the MySQL configuration
it would crash on launch).
This was resolved by upgrading MySQL to 5.7 (I think at least >=5.6.6
would have been needed) which introduced a _large_ amount of additional
work due to our db being so old.
3)
After initially enabling IPv6 support I saw failed connections to high
numbered ports (4xxxx-5xxxx) from our DPM head node to our storage
nodes.
This is still a bit of a mystery as this port range isn't in our site
config and we don't see any traffic on this port range over IPv4.
My assumption at this point is that there might have been a
misconfiguration as when we added `export
GLOBUS_TCP_PORT_RANGE="20000,25000"` to /etc/sysconfig/globus on all
machines and rebooted all services (again) the problem went away.
However this was also discovered(and fixed?) before we had to migrate
our MySQL.
Hope this helps anyone and thanks for any suggestions of anything I may
have done incorrectly,
At the moment our storage now appears to be correctly accepting IPv4/v6
connections and we didn't have to modify any other site configuration
information.
Best Regards,
Rob
--
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.
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