PacketPro 1.7.0

Posted on Tuesday, 15th January, 2008 in Life

After blogging the last time about the PacketPro 450 LoadBalancer appliance, the guys over at teamix seem to have taken that to heart and implemented a rather nifty thing for their new release.

It’s called “Port forwarding“, which is basically what you’d figure from the name. It bounces ports around the load balancer, but saves you from creating a separate virtual server (and adding the physical servers to that one), but also saves you from modifying the syslog-ng configuration on the balanced servers.

No Comments | Tags: , , ,


Typo3 and MySQL replication

Posted on Saturday, 8th September, 2007 in Life

Apparently the TYPO3 version we are using, doesn’t play too nice with the MySQL Master< ->Master replication.

Sometimes, something like this is going to happen:

070826  0:44:32 [ERROR] Slave: Error 'Duplicate entry '75-222419149' for key 1' on query. Default database: 't3nb'. Query: 'INSERT INTO cache_pagesection
070826  0:44:32 [ERROR] Error running query, slave SQL thread aborted. Fix the problem, and restart the slave SQL thread with "SLAVE START". We stopped at log 'dbc-mysql1.000192' position 611861372

Well, as you can see from the last line in the log, the Slave-SQL thread found a duplicate entry and thought it is smart to just turn off the thread instead of disregarding the just made entry. So from now on, both databases drift since there ain’t no replication anymore until someone kick starts the replication again (someone being me).

Anyway, I think I finally traced the fucker down, supposedly one of the problematic cases is located in t3lib/class.t3lib_tstemplate.php on line 362.

$GLOBALS['TYPO3_DB']->exec_DELETEquery('cache_pagesection', 'page_id='.intval($GLOBALS['TSFE']->id).' AND mpvar_hash='.t3lib_div::md5int($GLOBALS['TSFE']->MP));
$GLOBALS['TYPO3_DB']->exec_INSERTquery('cache_pagesection', $insertFields);

Basically what TYPO3 is doing is a DELETE and an INSERT right afterwards. But apparently, it doesn’t check whether the DELETE even succeeded. I hacked it for now, simply adding this:

-                               $GLOBALS['TYPO3_DB']->exec_INSERTquery('cache_pagesection', $insertFields);
+                               // Only insert a new cache entry with the same value, if the DELETE succeeded
+                               if ($GLOBALS['TYPO3_DB']->sql_affected_rows() == 1)
+                                       $GLOBALS['TYPO3_DB']->exec_INSERTquery('cache_pagesection', $insertFields);
+

Sadly, this looks more and more like a race-condition between the two boxes (as in the replication / UPDATE being too slow), when users visit a edited site, that hasn’t had it’s cache regenerated yet. Problem is, it ain’t just this single spot, but also the search indexing, image cache and the whole page cache. For now we switched the cluster to active/passive load balancing, till we have a chance to see if a newer TYPO3 fixes those issues.

No Comments | Tags: , , , , ,


miimon, arp_interval and the code

Posted on Wednesday, 4th July, 2007 in Life

After today’s adventure with the kernel bonding, I just took a look at the code …

         if (miimon) {
                 printk(KERN_INFO DRV_NAME
                        ": MII link monitoring set to %d msn",
                        miimon);
         } else if (arp_interval) {
                 int i;
 
                 printk(KERN_INFO DRV_NAME
                        ": ARP monitoring set to %d ms, validate %s, with %d target(s):",
                        arp_interval,
                        arp_validate_tbl[arp_validate_value].modename,
                        arp_ip_count);
 
                 for (i = 0; i < arp_ip_count; i++)
                         printk (" %s", arp_ip_target[i]);
 
                 printk("n");
 
         } else {
                 /* miimon and arp_interval not set, we need one so things
                  * work as expected, see bonding.txt for details
                  */
                 printk(KERN_WARNING DRV_NAME
                        ": Warning: either miimon or arp_interval and "
                        "arp_ip_target module parameters must be specified, "
                        "otherwise bonding will not detect link failures! see "
                        "bonding.txt for details.n");
         }

If I read it right, you only get the KERN_WARNING for “either miimon or arp_interval” only if miimon or arp_interval isn’t set … but at least my config says it is .. *shrug* .. bed time for me :roll:

No Comments | Tags: , , ,