Raid Chunk Sizes for DSS type DB - Mailing list pgsql-general

From Ow Mun Heng
Subject Raid Chunk Sizes for DSS type DB
Date
Msg-id 1193708557.32580.11.camel@neuromancer.home.net
Whole thread Raw
Responses Re: Raid Chunk Sizes for DSS type DB  ("Joshua D. Drake" <jd@commandprompt.com>)
Re: Raid Chunk Sizes for DSS type DB  (Richard Broersma Jr <rabroersma@yahoo.com>)
List pgsql-general
It's not an optimal setup but since I only have 3x500G drives to play
with, I can't build a Raid10, so I'm going for Raid5 to test out
capability before I decide on Raid5 vs Raid1 tradeoff. (Raid1 = No Fault
tolerance since 3 drives)

Anyway.. I'm trying to figure out the chunk size for the raid. I'm using
4k chunks since I'm reading that for DSS type queries, lots of Large
Reads, I should be using small chunks. [1] and I've aligned the disks
per [2]

and my stride will 3 for ext3

mdadm --create --verbose /dev/md1 --level=5 --raid-devices=3 --chunk=4 /dev/sdd1 /dev/sde1 /dev/sdf1
mkfs.ext3 -E stride=3 -O dir_index /dev/md1
mount /dev/md1 /pgsql/ -o noatime,data=writeback


[1] http://wiki.centos.org/HowTos/Disk_Optimization
[2] http://www.pythian.com/blogs/411/aligning-asm-disks-on-linux

Just wondering if there's any suggestions/comments on this from the PG ppl here.

Thanks for any/all comments.


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