From: Richard Neill
Subject: Re: SSD + RAID
Date: ,
Msg-id: 4B06E72D.20504@cam.ac.uk
(view: Whole thread, Raw)
In response to: Re: SSD + RAID  (Axel Rau)
Responses: Re: SSD + RAID  (Greg Smith)
List: pgsql-performance

Tree view

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, )

Axel Rau wrote:
>
> Am 13.11.2009 um 14:57 schrieb Laszlo Nagy:
>
>> I was thinking about ARECA 1320 with 2GB memory + BBU. Unfortunately,
>> I cannot find information about using ARECA cards with SSD drives.
> They told me: currently not supported, but they have positive customer
> reports. No date yet for implementation of the TRIM command in firmware.
> ...
>> My other option is to buy two SLC SSD drives and use RAID1. It would
>> cost about the same, but has less redundancy and less capacity. Which
>> is the faster? 8-10 MLC disks in RAID 6 with a good caching
>> controller, or two SLC disks in RAID1?

Despite my other problems, I've found that the Intel X25-Es work
remarkably well. The key issue for short,fast transactions seems to be
how fast an fdatasync() call can run, forcing the commit to disk, and
allowing the transaction to return to userspace.
With all the caches off, the intel X25-E beat a standard disk by a
factor of about 10.
Attached is a short C program which may be of use.


For what it's worth, we have actually got a pretty decent (and
redundant) setup using a RAIS array of RAID1.


[primary server]

SSD }
      }  RAID1  -------------------}  DRBD --- /var/lib/postgresql
SSD }                            }
                                   }
                                   }
                                   }
                                   }
[secondary server]               }
                                   }
SSD }                            }
      }  RAID1 --------gigE--------}
SSD }



The servers connect back-to-back with a dedicated Gigabit ethernet
cable, and DRBD is running in protocol B.

We can pull the power out of 1 server, and be using the next within 30
seconds, and with no dataloss.


Richard



#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#define NUM_ITER 1024

int main ( int argc, char **argv ) {
    const char data[] = "Liberate";
    size_t data_len = strlen ( data );
    const char *filename;
    int fd;
    unsigned int i;

    if ( argc != 2 ) {
        fprintf ( stderr, "Syntax: %s output_file\n", argv[0] );
        exit ( 1 );
    }
    filename = argv[1];
    fd = open ( filename, ( O_WRONLY | O_CREAT | O_EXCL ), 0666 );
    if ( fd < 0 ) {
        fprintf ( stderr, "Could not create \"%s\": %s\n",
              filename, strerror ( errno ) );
        exit ( 1 );
    }

    for ( i = 0 ; i < NUM_ITER ; i++ ) {
        if ( write ( fd, data, data_len ) != data_len ) {
            fprintf ( stderr, "Could not write: %s\n",
                  strerror ( errno ) );
            exit ( 1 );
        }
        if ( fdatasync ( fd ) != 0 ) {
            fprintf ( stderr, "Could not fdatasync: %s\n",
                  strerror ( errno ) );
            exit ( 1 );
        }
    }
    return 0;
}



pgsql-performance by date:

From: Greg Smith
Date:
Subject: Re: SSD + RAID
From: Merlin Moncure
Date:
Subject: Re: SSD + RAID