Re: PostgreSQL+ZFS

[Atif CEYLAN <mehmet@atifceylan.com>]

On 01/01/2011 06:24 PM, Stan Hoeppner wrote:
> Atif CEYLAN put forth on 12/31/2010 4:58 PM:
>    
> > Hi all,
> > I have a large postgresql database system and I want to migrate to a new
> > and fast storage system (10 Gbp/s FC network). But 150x3 ssd disk on my
> > db server and I want to use ext4 file system (raid5) at the ssd disks as
> > xlog storage or use zfs (raidz) as disk buffer cache.
> > What is your idea?
> >      
> In as few words as possible?  You're a nut job.  The mere mention of
> using FUSE ZFS in any production context on Linux proves it.  As does
> mentioning running RAID 5 on 3 SSDs, or any SSDs for that matter, or
> running RAID 5 in a db context, for that matter.
>
> What exactly are you really asking for advice on?  You've left out the
> most important detail:  what your database application is, and what you
> actually do with it.
>
> What type of data does your db house?
>    
 %95 text type %5 blob type records.
> How much data?  Total GB?
>    
~300 GB
> Are you currently short of space?
>    
no, don't need more space.
> Are you currently short of IOPS capacity?
>    
yes
> How many concurrent transactions?
>    
minimum 100-200 transactions, maximum  800-1000 concurrent transactions.
> What types of transactions?
>    
usually update and insert
> Is it read only/heavy or transactional like point of sale?
>    
I didn't understand this.
> What is a "large postgresql database system"?  What exactly do you mean
> by this?  Does large mean heavy transaction load?   Or does it simply
> mean lots of data housed?  Or is it simply BS?
>    
heavy transaction load.
> Giving any relevant recommendations WRT SAN, SSD, or filesystem
> performance is meaningless at this point when you've given exactly zero
> details about your database workload.  The workload drives all other
> aspects of the system design.  For all we know your db could simply
> contain your pirated music collection and would be completely
> comfortable on a single 1TB SATA disk.
>
> Give us the pertinent details and we can probably give you some decent
> "ideas", as you requested.
>
>    


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