From: david@lang.hm
Subject: Re: SCSI vs SATA
Date: ,
Msg-id: Pine.LNX.4.64.0704032106210.30746@asgard.lang.hm
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In response to: Re: SCSI vs SATA  (Geoff Tolley)
Responses: Re: SCSI vs SATA  ("Peter Kovacs")
Re: SCSI vs SATA  (Geoff Tolley)
List: pgsql-performance

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SCSI vs SATA  ("", )
 Re: SCSI vs SATA  (Ron, )
  Re: SCSI vs SATA  (Ron, )
   Re: SCSI vs SATA  (Geoff Tolley, )
    Re: SCSI vs SATA  (, )
     Re: SCSI vs SATA  ("Peter Kovacs", )
      Re: SCSI vs SATA  (Andreas Kostyrka, )
       Re: SCSI vs SATA  (Alvaro Herrera, )
        Re: SCSI vs SATA  ("Peter Kovacs", )
         Re: SCSI vs SATA  (Alvaro Herrera, )
          Re: SCSI vs SATA  (Andreas Kostyrka, )
         Re: SCSI vs SATA  (, )
       Re: SCSI vs SATA  (Rod Taylor, )
     Re: SCSI vs SATA  (Geoff Tolley, )
    Re: SCSI vs SATA  ("", )
     Re: SCSI vs SATA  ("Joshua D. Drake", )
      Re: SCSI vs SATA  (Stefan Kaltenbrunner, )
       Re: SCSI vs SATA  ("Joshua D. Drake", )
        Re: SCSI vs SATA  (Stefan Kaltenbrunner, )
         Can't drop tablespace or user after disk gone  ("Craig A. James", )
          Re: Can't drop tablespace or user after disk gone  (Tom Lane, )
       Re: SCSI vs SATA  ("James Mansion", )
      Re: SCSI vs SATA  (Andreas Kostyrka, )
       Re: SCSI vs SATA  ("Joshua D. Drake", )
        Re: SCSI vs SATA  (, )
         Re: SCSI vs SATA  (Geoff Tolley, )
         Re: SCSI vs SATA  (Bruce Momjian, )
          Re: SCSI vs SATA  ("Joshua D. Drake", )
           Re: SCSI vs SATA  (Bruce Momjian, )
            Re: SCSI vs SATA  ("James Mansion", )
             Re: SCSI vs SATA  (Tom Lane, )
              Re: SCSI vs SATA  (Scott Marlowe, )
               Re: SCSI vs SATA  (Ron, )
                Re: SCSI vs SATA  (, )
                 Re: SCSI vs SATA  (Tom Lane, )
                  Re: SCSI vs SATA  (Greg Smith, )
                   Re: SCSI vs SATA  (Tom Lane, )
                    Re: SCSI vs SATA  (Geoffrey, )
                  Re: SCSI vs SATA  (Michael Stone, )
                   Re: SCSI vs SATA  (Geoffrey, )
               Re: SCSI vs SATA  ("James Mansion", )
                Re: SCSI vs SATA  (Scott Marlowe, )
                 Re: SCSI vs SATA  (, )
                  Re: SCSI vs SATA  (Ron, )
                   Re: SCSI vs SATA  (, )
                    Re: SCSI vs SATA  (Richard Troy, )
                    Re: SCSI vs SATA  (Ron, )
                     Re: SCSI vs SATA  (, )
                      Re: SCSI vs SATA  (Ron, )
                       Re: SCSI vs SATA  (Mark Kirkwood, )
                   Re: SCSI vs SATA  (Michael Stone, )
                    Re: SCSI vs SATA  (Ron, )
                     Re: SCSI vs SATA  (Michael Stone, )
                      Re: SCSI vs SATA  (Ron, )
                       Re: SCSI vs SATA  (Michael Stone, )
                        Re: SCSI vs SATA  (Ron, )
                         Re: SCSI vs SATA  (Michael Stone, )
                 Re: SCSI vs SATA  (Greg Smith, )
                  Re: SCSI vs SATA  (Scott Marlowe, )
                   Re: SCSI vs SATA  (Greg Smith, )
                   Re: SCSI vs SATA  (, )
                    Re: SCSI vs SATA  (Charles Sprickman, )
                     Re: SCSI vs SATA  (, )
                     Re: SCSI vs SATA  (Andreas Kostyrka, )
                   Re: SCSI vs SATA  (Bruce Momjian, )
                    Re: SCSI vs SATA  (Ron, )
                     Re: SCSI vs SATA  (, )
                      Re: SCSI vs SATA  (Ron, )
                       Re: SCSI vs SATA  (, )
                        Re: SCSI vs SATA  ("Joshua D. Drake", )
                        Re: SCSI vs SATA  (Ron, )
                       Re: SCSI vs SATA  (, )
                 Re: SCSI vs SATA  ("James Mansion", )
           Re: SCSI vs SATA  (Carlos Moreno, )
            Re: SCSI vs SATA  ("", )
             Re: SCSI vs SATA  (Arjen van der Meijden, )
             Re: SCSI vs SATA  (Heikki Linnakangas, )
             Re: SCSI vs SATA  (Ron, )
              Re: SCSI vs SATA  ("", )
               Re: SCSI vs SATA  ("Joshua D. Drake", )
               Re: SCSI vs SATA  ("Alex Deucher", )
               Re: SCSI vs SATA  (Arjen van der Meijden, )
               Re: SCSI vs SATA  (, )
     Re: SCSI vs SATA  (Geoff Tolley, )
     Re: SCSI vs SATA  (Scott Marlowe, )
      Re: SCSI vs SATA  (Jeff Frost, )
       Re: SCSI vs SATA  ("", )
 Re: SCSI vs SATA  ("Brian A. Seklecki", )
 Re: SCSI vs SATA  (Ron Mayer, )
 Re: SCSI vs SATA  (Ron, )
 Re: SCSI vs SATA  (Arjen van der Meijden, )
  Re: SCSI vs SATA  ("", )
   Re: SCSI vs SATA  (Arjen van der Meijden, )

On Tue, 3 Apr 2007, Geoff Tolley wrote:

>
> Ron wrote:
>>  At 07:07 PM 4/3/2007, Ron wrote:
>> >  For random IO, the 3ware cards are better than PERC
>> >
>> > >  Question: will 8*15k 73GB SCSI drives outperform 24*7K 320GB SATA II
>> >  drives?
>> >
>> >  Nope.  Not even if the 15K 73GB HDs were the brand new Savvio 15K
>> >  screamers.
>> >
>> >  Example assuming 3.5" HDs and RAID 10 => 4 15K 73GB vs 12 7.2K 320GB
>> >  The 15K's are 2x faster rpm, but they are only ~23% the density =>
>> >  advantage per HD to SATAs.
>> >  Then there's the fact that there are 1.5x as many 7.2K spindles as 15K
>> >  spindles...
>>  Oops make that =3x= as many 7.2K spindles as 15K spindles...
>
> I don't think the density difference will be quite as high as you seem to
> think: most 320GB SATA drives are going to be 3-4 platters, the most that a
> 73GB SCSI is going to have is 2, and more likely 1, which would make the
> SCSIs more like 50% the density of the SATAs. Note that this only really
> makes a difference to theoretical sequential speeds; if the seeks are random
> the SCSI drives could easily get there 50% faster (lower rotational latency
> and they certainly will have better actuators for the heads). Individual 15K
> SCSIs will trounce 7.2K SATAs in terms of i/os per second.

true, but with 3x as many drives (and 4x the capacity per drive) the SATA
system will have to do far less seeking

for that matter, with 20ish 320G drives, how large would a parition be
that only used the outer pysical track of each drive? (almost certinly
multiple logical tracks) if you took the time to set this up you could
eliminate seeking entirely (at the cost of not useing your capacity, but
since you are considering a 12x range in capacity, it's obviously not your
primary concern)

> If you care about how often you'll have to replace a failed drive, then the
> SCSI option no question, although check the cases for hot-swapability.

note that the CMU and Google studies both commented on being surprised at
the lack of difference between the reliability of SCSI and SATA drives.

David Lang


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From: Arnau
Date:
Subject: Re: Equivalents in PostgreSQL of MySQL's "ENGINE=MEMORY" "MAX_ROWS=1000"
From: "Peter Kovacs"
Date:
Subject: Re: SCSI vs SATA