On Mon, Oct 5, 2009 at 7:30 AM, Nikolas Everett <nik9000@gmail.com> wrote:
>
>> But you should plan on partitioning to multiple db servers up front
>> and save pain of conversion later on. A dual socket motherboard with
>> 16 to 32 SAS drives and a fast RAID controller is WAY cheaper than a
>> similar machine with 4 to 8 sockets is gonna be. And if you gotta go
>> there anyway, might as well spend your money on other stuff.
>>
>
> I agree. If you can partition that sensor data across multiple DBs and have
> your application do the knitting you might be better off. If I may be so
> bold, you might want to look at splaying the systems out across your
> backends. I'm just trying to think of a dimension that you won't want to
> aggregate across frequently.
Agreed back. If there's a logical dimension to split data on, it
becomes much easier to throw x machines at it than to try and build
one ubermachine to handle it all.
> On the other hand, one of these 16 to 32 SAS drive systems with a raid card
> will likely get you a long way.
Yes they can. We're about to have to add a third db server, cause
this is the load on our main slave db:
procs -----------memory---------- ---swap-- -----io---- --system--
-----cpu------
r b swpd free buff cache si so bi bo in cs us sy id wa st
22 0 220 633228 229556 28432976 0 0 638 304 0 0 21
3 73 3 0
19 1 220 571980 229584 28435180 0 0 96 1111 7091 9796 90
6 4 0 0
20 0 220 532208 229644 28440244 0 0 140 3357 7110 9175 90
6 3 0 0
19 1 220 568440 229664 28443688 0 0 146 1527 7765 10481
90 7 3 0 0
9 1 220 806668 229688 28445240 0 0 99 326 6661 10326
89 6 5 0 0
9 0 220 814016 229712 28446144 0 0 54 1544 7456 10283
90 6 4 0 0
11 0 220 782876 229744 28447628 0 0 96 406 6619 9354 90
5 5 0 0
29 1 220 632624 229784 28449964 0 0 113 994 7109 9958 90
7 3 0 0
It's working fine. This has a 16 15k5 SAS disks. A 12 Disk RAID-10,
a 2 disk mirror for pg_xlog / OS, and two spares. It has 8 opteron
cores and 32Gig ram. We're completely CPU bound because of the type of
app we're running. So time for slave number 2...
