On 11/4/2013 1:27 PM, Phil Stracchino wrote: > On 11/04/13 13:00, Josh Fisher wrote: >> I would add that it is critical (IMO) to place the DB storage on >> different physical drives than those holding the Bacula spool area. At >> the end of a job Bacula SD must read the spooled attributes and update >> the catalog. If spooled attributes and catalog are on the same spindles, >> then the disk thrashing negates the advantage of attribute spooling. I >> might also add that placing the catalog on SSD resulted in a hefty >> performance gain. > Seconded. Wherever possible, you always want your DB either on separate > spindles or on solid-state media where seek latency is not an issue. > >> As for clustering using DRBD, the catalog and spool area should still be >> on different spindles. > Honestly, based upon experience as a DBA at a hosting company that hosts > MANY customers using MySQL, my first advice on using MySQL on top of > DRBD would be "Just don't." I could cite lists of customers who have > had complete unrecoverable DB losses as a result of problems or > interactions involving DRBD, and had to rebuild from DB backups. If > you're going to cluster MySQL, use a shared-nothing configuration if you > possibly can.
Interesting. I am curious as to what DRBD replication mode was used. In mode C (synchronous replication) a write operation does not complete until it has been written to both nodes, so is essentially network RAID-1 and guaranteed not to lose data in the event of a forced fail-over. It is of course slower, so some may be tempted to use mode A (asynchronous replication) which can and will lose data in the event of a fail-over. Mode A is faster and reasonable for some uses, but only mode C should ever be used for database storage. I have been using MySQL on DRBD in mode C for quite some time and have seen drive failures, NIC failures, and node failures without any data loss or db problems I could attribute to DRBD. ------------------------------------------------------------------------------ Android is increasing in popularity, but the open development platform that developers love is also attractive to malware creators. Download this white paper to learn more about secure code signing practices that can help keep Android apps secure. http://pubads.g.doubleclick.net/gampad/clk?id=65839951&iu=/4140/ostg.clktrk _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
