Re: suggestions for postgresql setup on Dell 2950 , PERC6i controller

Scott Carey wrote:
> You probably don’t want a single array with more than 32 drives anyway,
> its almost always better to start carving out chunks and using software
> raid 0 or 1 on top of that for various reasons. I wouldn’t put more than
> 16 drives in one array on any of these RAID cards, they’re just not
> optimized for really big arrays and tend to fade between 6 to 16 in one
> array, depending on the quality.

This is what I'm looking at now. The server I'm working on at the moment
currently has a PERC6/e and 3xMD1000s which needs to be tested in a few
setups. I need to code a benchmarker yet (I haven't found one yet that
can come close to replicating our DB usage patterns), but I intend to try:

1. 3x h/w RAID10 (one per shelf), sofware RAID0
2. lots x h/w RAID1, software RAID0 if the PERC will let me create
enough arrays
3. Pure s/w RAID10 if I can convince the PERC to let the OS see the disks
4. 2x h/w RAID30, software RAID0

I'm not holding much hope out for the last one :)

I'm just glad work on a rewrite of my inherited backend systems should
start soon; get rid of the multi-TB MySQL hell and move to a distributed
PG setup on dirt cheap Dell R200s/blades

> You can do direct-attached storage to 100+ drives or more if you want.
> The price and manageability cost go up a lot if it gets too big
> however. Having global hot spare drives is critical. Not that the cost
> of using SAN’s and such is low... SAS expanders have made DAS with
> large arrays very accessible though.

For large storage arrays (RAID60 or similar) you can't beat a RAID
controller and disk shelf(s), especially if you keep the raidsets small
and use cheap ludicrous capacity SATA disks

You just need to be aware that performance doesn't scale well/easily
over 1-2 shelves on the things

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