From: Anj Adu <fotographs@gmail.com>
To: Greg Smith <greg@2ndquadrant.com>
Cc: pgsql-admin@postgresql.org
Subject: Re: more 10K disks or less 15K disks
Date: Wed, 28 Apr 2010 21:45:06 -0700
Message-ID: <u2zf2fd819a1004282145wc60c3b39o7f0679fec9f607f8@mail.gmail.com> (raw)
In-Reply-To: <4BD8DCEA.2020003@2ndquadrant.com>
References: <i2pf2fd819a1004281127sf91d988cua1d95d13d09dae09@mail.gmail.com>
<4BD8DCEA.2020003@2ndquadrant.com>
Thanks Greg
We do not archive the WALs. We use application-level replication to
achieve redundancy. WAL archiving was difficult to support with the
earlier hardware we had ( 6x300G 10K disks Dell 2850) given the
volumes we were dealing with. The RAID card should be from the same
manufacturer (LSI in Dell's case).
On our current system (6 x 450G 15K disks), we are able to sustain 100
million records/day but probably not more.
On Wed, Apr 28, 2010 at 6:12 PM, Greg Smith <greg@2ndquadrant.com> wrote:
> Anj Adu wrote:
>>
>> I am faced with a hardware choice for a postgres data warehouse
>> (extremely high volume inserts..over 200 million records a day)
>
> That's an average of 2314 per second, which certainly isn't easy to pull
> off. You suggested you're already running this app. Do you have any idea
> how high the volume of data going to the WAL is relative to everything else?
>
>> 12 x 600G disks (15K) (the new Dell Poweredge C server)
>> or
>> 24 x 600G (10K disks)
>>
>
> You can expect the 15K disks to be 30% (more sequential work) to 50%
> (random/commit work) faster than a similar 10K drive. So from most
> perspectives, twice as many 10K drives should be considerably faster. The
> main point of concern here is the commit rate, which you can't necessarily
> improve just by throwing drives at it. That's based on how fast the drives
> spin, so there's the potential to discover a 50% regression there compared
> to the setup you have right now. With the RAID card in there, it should be
> fine, but it's something to be concerned about.
>
> Also, you didn't mentioned the RAID card for the new system, and whether it
> would be the same in both setups or not. That can be as important as the
> drives when you have larger arrays. The LSI Megaraid card Dell is using for
> the Perc6i is quite fast, and you'll need to make sure you get something
> just as good for the new server.
>
> --
> Greg Smith 2ndQuadrant US Baltimore, MD
> PostgreSQL Training, Services and Support
> greg@2ndQuadrant.com www.2ndQuadrant.us
>
>
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To: pgsql-admin@postgresql.org
Cc: fotographs@gmail.com, greg@2ndquadrant.com
Subject: Re: more 10K disks or less 15K disks
In-Reply-To: <u2zf2fd819a1004282145wc60c3b39o7f0679fec9f607f8@mail.gmail.com>
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