From: david@lang.hm
Subject: Re: SSD + RAID
Date: ,
Msg-id: alpine.DEB.2.00.0911172247190.5646@asgard.lang.hm
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In response to: Re: SSD + RAID  (Greg Smith)
Responses: Re: SSD + RAID  (Scott Carey)
List: pgsql-performance

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SSD + RAID  (Laszlo Nagy, )
 Re: SSD + RAID  (Karl Denninger, )
  Re: SSD + RAID  (Laszlo Nagy, )
   Re: SSD + RAID  (Axel Rau, )
    Re: SSD + RAID  (Richard Neill, )
     Re: SSD + RAID  (Greg Smith, )
      Re: SSD + RAID  (Merlin Moncure, )
  Re: SSD + RAID  (Marcos Ortiz Valmaseda, )
 Re: SSD + RAID  (Scott Marlowe, )
  Re: SSD + RAID  (Merlin Moncure, )
   Re: SSD + RAID  (Scott Carey, )
    Re: SSD + RAID  (Merlin Moncure, )
 Re: SSD + RAID  (Heikki Linnakangas, )
  Re: SSD + RAID  (Merlin Moncure, )
   Re: SSD + RAID  (Heikki Linnakangas, )
    Re: SSD + RAID  (Merlin Moncure, )
     Re: SSD + RAID  (Heikki Linnakangas, )
      Re: SSD + RAID  (Merlin Moncure, )
  Re: SSD + RAID  (Laszlo Nagy, )
   Re: SSD + RAID  (Robert Haas, )
    Re: SSD + RAID  (Laszlo Nagy, )
 Re: SSD + RAID  (Greg Smith, )
  Re: SSD + RAID  (Karl Denninger, )
   Re: SSD + RAID  (Greg Smith, )
    Re: SSD + RAID  (Karl Denninger, )
     Re: SSD + RAID  (Scott Carey, )
      Re: SSD + RAID  (Tom Lane, )
       Re: SSD + RAID  (Jeff Janes, )
      Re: SSD + RAID  (Greg Smith, )
       Re: SSD + RAID  (Karl Denninger, )
    Re: SSD + RAID  (Brad Nicholson, )
     Re: SSD + RAID  (Dave Crooke, )
     Re: SSD + RAID  (Greg Smith, )
      Re: SSD + RAID  (Merlin Moncure, )
      Re: SSD + RAID  (Merlin Moncure, )
       Re: SSD + RAID  (Brad Nicholson, )
        Re: SSD + RAID  (Scott Marlowe, )
       Re: SSD + RAID  (Peter Eisentraut, )
       Re: SSD + RAID  (Greg Smith, )
        Re: SSD + RAID  (Merlin Moncure, )
         Re: SSD + RAID  (Greg Smith, )
          Re: SSD + RAID  (, )
           Re: SSD + RAID  (Scott Carey, )
            Re: SSD + RAID  (Merlin Moncure, )
             Re: SSD + RAID  (Scott Marlowe, )
              Re: SSD + RAID  (Greg Smith, )
               Re: SSD + RAID  (Merlin Moncure, )
                Re: SSD + RAID  (Scott Marlowe, )
        Re: SSD + RAID  (Mark Mielke, )
        Re: SSD + RAID  (Scott Carey, )
         Re: SSD + RAID  (Greg Smith, )
        Re: SSD + RAID  (Bruce Momjian, )
         Re: SSD + RAID  (Ron Mayer, )
          Re: SSD + RAID  (Bruce Momjian, )
           Re: SSD + RAID  (Greg Smith, )
            Re: SSD + RAID  (Bruce Momjian, )
             Re: SSD + RAID  (Ron Mayer, )
              Re: SSD + RAID  (Bruce Momjian, )
           Re: SSD + RAID  (Ron Mayer, )
  Re: SSD + RAID  (Merlin Moncure, )
  Re: SSD + RAID  (Matthew Wakeling, )
   Re: SSD + RAID  (Bruce Momjian, )
    Re: SSD + RAID  (Dan Langille, )
     Re: SSD + RAID  (Bruce Momjian, )
      Re: SSD + RAID  (Scott Carey, )
       Re: SSD + RAID  (Bruce Momjian, )
        Re: SSD + RAID  (Ron Mayer, )
         Re: SSD + RAID  (Greg Smith, )
          Re: SSD + RAID  (Arjen van der Meijden, )
           Re: SSD + RAID  (Greg Smith, )
            Re: SSD + RAID  (Mark Mielke, )
             Re: SSD + RAID  (Greg Smith, )
              Re: SSD + RAID  (Scott Marlowe, )
               Re: SSD + RAID  (Scott Marlowe, )
                Re: SSD + RAID  ("Pierre C", )
                 Re: SSD + RAID  (Nikolas Everett, )
                 Re: SSD + RAID  (Scott Carey, )
          Re: SSD + RAID  (Bruce Momjian, )
           Re: SSD + RAID  (Ron Mayer, )
            Re: SSD + RAID  (Greg Smith, )
            Re: SSD + RAID  (, )
             Re: SSD + RAID  (, )
              Re: SSD + RAID  (Aidan Van Dyk, )
               Re: SSD + RAID  (, )
                Re: SSD + RAID  (Mark Mielke, )
                Re: SSD + RAID  (Dave Crooke, )
          Re: SSD + RAID  (Bruce Momjian, )
           Re: SSD + RAID  (Greg Smith, )
            Re: SSD + RAID  (Bruce Momjian, )
             Re: SSD + RAID  (Ron Mayer, )
              Re: SSD + RAID  (Greg Smith, )
               Re: SSD + RAID  (Bruce Momjian, )
              Re: SSD + RAID  (Bruce Momjian, )
               Re: SSD + RAID  (Greg Smith, )
                Re: SSD + RAID  (Ron Mayer, )
               Re: SSD + RAID  ("Pierre C", )
         Re: SSD + RAID  (Bruce Momjian, )
 Re: SSD + RAID  ("Fernando Hevia", )
  Re: SSD + RAID  (Greg Smith, )
 Re: SSD + RAID  ("Kenny Gorman", )
  Re: SSD + RAID  (Kenny Gorman, )
 Re: SSD + RAID  (Lists, )
  Re: SSD + RAID  (Ivan Voras, )
   Re: SSD + RAID  (Laszlo Nagy, )
    Re: SSD + RAID  (Craig Ringer, )
     Re: SSD + RAID  (Laszlo Nagy, )
      Re: SSD + RAID  (Craig Ringer, )
       Re: SSD + RAID  (Laszlo Nagy, )
     Re: SSD + RAID  (Craig James, )
      Re: SSD + RAID  (Heikki Linnakangas, )
     Re: SSD + RAID  (Scott Carey, )
      Re: SSD + RAID  (Craig Ringer, )
       Re: SSD + RAID  (Anton Rommerskirchen, )
        Re: SSD + RAID  (Brad Nicholson, )
      Re: SSD + RAID  (Greg Smith, )
       Re: SSD + RAID  (Matthew Wakeling, )
       Re: SSD + RAID  (Scott Carey, )

On Wed, 18 Nov 2009, Greg Smith wrote:

> Merlin Moncure wrote:
>> But what's up with the 400 iops measured from bonnie++?
> I don't know really.  SSD writes are really sensitive to block size and the
> ability to chunk writes into larger chunks, so it may be that Peter has just
> found the worst-case behavior and everybody else is seeing something better
> than that.
>
> When the reports I get back from people I believe are competant--Vadim,
> Peter--show worst-case results that are lucky to beat RAID10, I feel I have
> to dismiss the higher values reported by people who haven't been so careful.
> And that's just about everybody else, which leaves me quite suspicious of the
> true value of the drives.  The whole thing really sets off my vendor hype
> reflex, and short of someone loaning me a drive to test I'm not sure how to
> get past that.  The Intel drives are still just a bit too expensive to buy
> one on a whim, such that I'll just toss it if the drive doesn't live up to
> expectations.

keep in mind that bonnie++ isn't always going to reflect your real
performance.

I have run tests on some workloads that were definantly I/O limited where
bonnie++ results that differed by a factor of 10x made no measurable
difference in the application performance, so I can easily believe in
cases where bonnie++ numbers would not change but application performance
could be drasticly different.

as always it can depend heavily on your workload. you really do need to
figure out how to get your hands on one for your own testing.

David Lang


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