Re: Huge Data sets, simple queries

От: PFC
Тема: Re: Huge Data sets, simple queries
Дата: ,
Msg-id: op.s39morhucigqcu@apollo13
(см: обсуждение, исходный текст)
Ответ на: Re: Huge Data sets, simple queries  ("Luke Lonergan")
Ответы: Re: Huge Data sets, simple queries  ("Luke Lonergan")
Список: pgsql-performance

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Huge Data sets, simple queries  ("Mike Biamonte", )
 Re: Huge Data sets, simple queries  ("Jeffrey W. Baker", )
 Re: Huge Data sets, simple queries  (Tom Lane, )
  Re: Huge Data sets, simple queries  ("Jeffrey W. Baker", )
   Re: Huge Data sets, simple queries  (Tom Lane, )
    Re: Huge Data sets, simple queries  (Tom Lane, )
 Re: Huge Data sets, simple queries  ("Luke Lonergan", )
  Re: Huge Data sets, simple queries  (hubert depesz lubaczewski, )
   Re: Huge Data sets, simple queries  (Michael Stone, )
  Re: Huge Data sets, simple queries  ("Jim C. Nasby", )
   Re: Huge Data sets, simple queries  ("Luke Lonergan", )
    Re: Huge Data sets, simple queries  (Kevin, )
    Re: Huge Data sets, simple queries  ("Jim C. Nasby", )
     Re: Huge Data sets, simple queries  ("Luke Lonergan", )
      Re: Huge Data sets, simple queries  ("Jim C. Nasby", )
       Re: Huge Data sets, simple queries  ("Luke Lonergan", )
        Re: Huge Data sets, simple queries  ("Jim C. Nasby", )
    Re: Huge Data sets, simple queries  ("Jeffrey W. Baker", )
     Re: Huge Data sets, simple queries  ("Luke Lonergan", )
      Re: Huge Data sets, simple queries  (PFC, )
       Re: Huge Data sets, simple queries  ("Luke Lonergan", )
      Re: Huge Data sets, simple queries  ("Steinar H. Gunderson", )
       Re: Huge Data sets, simple queries  ("Luke Lonergan", )
      Re: Huge Data sets, simple queries  ("Jeffrey W. Baker", )
       Re: Huge Data sets, simple queries  ("Luke Lonergan", )
        Re: Huge Data sets, simple queries  ("Jeffrey W. Baker", )
         Re: Huge Data sets, simple queries  (PFC, )
          Re: Huge Data sets, simple queries  ("Luke Lonergan", )
           Re: Huge Data sets, simple queries  ("Steinar H. Gunderson", )
           Re: Huge Data sets, simple queries  (Mike Rylander, )
         Re: Huge Data sets, simple queries  ("Luke Lonergan", )
       Re: Huge Data sets, simple queries  (Michael Stone, )
     Re: Huge Data sets, simple queries  (Alan Stange, )
 Re: Huge Data sets, simple queries  ("Luke Lonergan", )
  Re: Huge Data sets, simple queries  ("Jeffrey W. Baker", )
  Re: Huge Data sets, simple queries  (Charles Sprickman, )
   Re: Huge Data sets, simple queries  ("Luke Lonergan", )
  Re: Huge Data sets, simple queries  (hubert depesz lubaczewski, )
   Re: Huge Data sets, simple queries  ("Luke Lonergan", )
 Re: Huge Data sets, simple queries  (Michael Adler, )
 Re: Huge Data sets, simple queries  ("Craig A. James", )

>> Linux does balanced reads on software
>> mirrors.  I'm not sure why you think this can't improve bandwidth.  It
>> does improve streaming bandwidth as long as the platter STR is more than
>> the bus STR.
>
> ... Prove it.
>

    (I have a software RAID1 on this desktop machine)

    It's a lot faster than a single disk for random reads when more than 1
thread hits the disk, because it distributes reads to both disks. Thus,
applications start faster, and the machine is more reactive even when the
disk is thrashing. Cron starting a "updatedb" is less painful. It's cool
for desktop use (and of course it's more reliable).

    However large reads (dd-style) are just the same speed as 1 drive. I
guess you'd need a humongous readahead in order to read from both disks.


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