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Re: SAN performance

From: "Anjan Dave" <adave(at)vantage(dot)com>
To: "Mr Pink" <mr_pink_is_the_only_pro(at)yahoo(dot)com>,<pgsql-performance(at)postgresql(dot)org>
Subject: Re: SAN performance
Date: 2004-09-23 18:05:05
Message-ID: 4BAFBB6B9CC46F41B2AD7D9F4BBAF78509853D@vt-pe2550-001.vantage.vantage.com (view raw or flat)
Thread:
Lists: pgsql-performance
I believe 1/0 or 1+0 is aka RAID-10. CX300 doesn't support 0+1.
 
So far i am aware of two things, the cache page size is 8KB (can be increased or decreased), and the stripe element size of 128 sectors default.
 
Thanks,
Anjan

	-----Original Message----- 
	From: Mr Pink [mailto:mr_pink_is_the_only_pro(at)yahoo(dot)com] 
	Sent: Thu 9/23/2004 11:39 AM 
	To: Anjan Dave; pgsql-performance(at)postgresql(dot)org 
	Cc: 
	Subject: Re: [PERFORM] SAN performance
	
	

	Hi, 

	I expect you mean RAID 1/0 or 1+0 since the CX300 didn't support RAID 10 last time I looked. 

	Whether you are using a SAN or not, you should consider putting the WAL files (pg_xlog folder) on 
	seperate diskes from the DB. Since the log files are mostly written to, not read from you could 
	just use RAID 1. 

	It's a pity pg doesn't have a way to use a cluster of servers to get the most out of your 
	expensive SAN. 

	I read a comment earlier about setting block sizes to 8k to math pg's block size. Seems to make 
	sense, you should check it out. 

	Have fun, 
	Mr Pink 

	--- Anjan Dave <adave(at)vantage(dot)com> wrote: 

	> Hello, 
	> 
	>  
	> 
	> I'll be moving a DB from internal RAID-10 SCSI storage to an EMC CX300 
	> FC RAID-10 LUN, bound to the host. I've setup a test host machine and a 
	> test LUN. The /var/lib/pgsql/data folder is sym-linked to a partition on 
	> the LUN. 
	> 
	>  
	> 
	> Other than the shared_buffers, effective cache size, and sort memory, I 
	> am not sure if I need to change any other parameters in the 
	> postgresql.conf file for getting maximum performance from the EMC box. 
	> 
	>  
	> 
	> Is there a general guideline for setting up postgres database and the 
	> tunable parameters on a SAN, especially for EMC? 
	> 
	>  
	> 
	> Appreciate any help, 
	> 
	>  
	> 
	> Thanks, 
	> Anjan 
	> 
	> 



	        
	                
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