Re: Hardware advice

Based on what you've said, I would guess you are considering the Dell PowerEdge 2650 since it has 5 drive bays.  If you
couldafford the rackspace and just a bit more money, I'd get the tower configuration 2600 with 6 drive bays (and rack
railsif needed - Dell even gives you a special rackmount faceplate if you order a tower with rack rails).  This would
allowyou to have this configuration, which I think would be about ideal for the price range you are looking at:
 
 
* Linux kernel RAID
* Dual processors - better than a single faster processor, especially with concurrent user load and software RAID on
topof that
 
* 2x36GB in RAID-1 (for OS and WAL)
* 4x146GB in RAID-10 (for data) (alternative: 4-disk RAID-5)
 
The RAID-10 array gives you the same amount of space you would have with a 3-disk RAID-5 and improved fault tolerance.
AlthoughI'm pretty sure your drives won't be hot-swappable with the software RAID - I've never actually had to do it.
 
 
I can't say I like Scott's idea much because the WAL and OS are competing for disk time with the data since they are on
thesame physical disk.  In a database that is mainly reads with few writes, this wouldn't be such a problem though.
 
 
Just my inexpert opinion,
 
Roman
 

    -----Original Message----- 
    From: Adam Witney [mailto:awitney@sghms.ac.uk] 
    Sent: Fri 5/30/2003 9:55 AM 
    To: scott.marlowe; Adam Witney 
    Cc: pgsql-performance 
    Subject: Re: [PERFORM] Hardware advice
    
    

    Hi scott,
    
    Thanks for the info
    
    > You might wanna do something like go to all 146 gig drives, put a mirror
    > set on the first 20 or so gigs for the OS, and then use the remainder
    > (5x120gig or so ) to make your RAID5.  The more drives in a RAID5 the
    > better, generally, up to about 8 or 12 as the optimal for most setups.
    
    I am not quite sure I understand what you mean here... Do you mean take 20Gb
    from each of the 5 drives to setup a 20Gb RAID 1 device? Or just from the
    first 2 drives?
    
    Thanks again for your help
    
    adam
    
    
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