Ricardo, Hello. I've moved your query to a more appropriate mailing list; on PERFORMANCE we discuss RAID all the time. If you don't mind wading through a host of opinions, you'll get plenty here. I've also cc'd our Brazillian PostgreSQL community.
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Everyone, please note that Ricardo is NOT subscribed so cc him on your responses. Here's Ricardo's question. My response is below it. =============================================== Let me introduce, I'm Ricardo Rezende and I'm SQL Magazine subeditor, from Brazil (http://www.sqlmagazine.com.br.). My goal in this first contact is to solve a doubt about PostgreSQL RDBMS. I'm writing an article about redundant storage technology, called RAID. The first part of the article can be found in http://www.sqlmagazine.com.br/colunistas.asp?artigo=Colunistas/RicardoRezende/06_Raid_P1.asp My ideia is to put, in the end of the article, a note about the better configuration of RAID to use with PostgreSQL and the reasons, including the reference to the autor/link to this information. Could you send me this information? Our magazine is being a reference between DBAs and Database Developers in Brazil and that is the reason to write "oficial" papers about PostgreSQL Thank you very much and I'm waiting for a return of this e-mail. ========================================================= The first and most important step for RAID performance with PostgreSQL is to get a card with onboard battery back-up and enable the write cache for the card. You do not want to enable the write cache *without* battery back-up because of the risk of data corruption after a power failure. If you can't afford this hardware, I would advise using software RAID over using a cheaper (< $300US) RAID card. The second step is to have lots of disks; 5 drives is a minimum for really good performance. 3-drive RAID5, in particular, is a poor performer for PostgreSQL, often resulting in I/O that is 40% or less as efficient as a single disk due to extremely slow random seeks and little parallelization. Once you have 6 drives or more, opinions are divided on whether RAID 10 or RAID 5 is better. I think it partly depends on your access pattern. -- --Josh Josh Berkus Aglio Database Solutions San Francisco ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
