Running large DB's on FreeBSD

[Chuck Swiger]

On Oct 23, 2006, at 4:44 PM, Mike Jakubik wrote:
>> Moderately...it kinda depends on the budget available.  I regard  
>> Solaris + Oracle as one of the most reliable combinations for  
>> moderate to extreme load, for a system that might well be in  
>> operation for five to ten years.  If I was going to do FreeBSD, I  
>> might look into Postgres instead of MySQL; well, I might look into  
>> something else than MySQL under many circumstances.  I've gotten  
>> some pretty good use out of OpenBase, for another choice.
>
> I believe the front-end application is MySQL dependent, but what is  
> so much better about PostgreSQL? I understand that it has some more  
> advanced features, but if they are not used, then what is the  
> advantage? (I really like the InnooDB storage in MySQL)

I'm not sure whether avoiding deadlocks and using row-level locking  
by default qualifies as "advanced features", but unless you use  
InnoDB with MySQL, you don't get that from MySQL.  Postgres has been  
around for a lot longer, and isn't as volatile as MySQL seems to be;  
also, it avoids some of the needless timer overhead that MySQL seems  
to enjoy, and the less-accurate-but-much-quicker gettimeofday() under  
Linux helps MySQL on that platform versus FreeBSD.

>> As for the disk configuration, using RAID-5 is one of the worst  
>> possible choices for a database; using multiple RAID-1 mirrors or  
>> a RAID-10 config would probably do a lot better in terms of  
>> performance and reliability.
>
> Is RAID5 really that bad when a lot of fast disks are used and the  
> controller has a decent cache with a BBWC? Thanks for the feedback  
> guys.

Yes, RAID-5 really can be that bad, unless your database is read-only  
or read-mostly.  Lots of small writes will perform badly under  
RAID-5, even with a battery-backed write-cache in write-back mode...

-- 
-Chuck