Backup write performance SSD , Sequential or Random ?

• kudz

  Mr or Mrs. 500

  Points: 542

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  January 9, 2019 at 1:05 am

  #376726

  Hi everyone!

  My setup has a spare SSD that I'm using to run some tests and while comparing the results of a FULL backup to it vs a CrystalDisk Benchmark I'm wondering if a FULL backup is really sequential.
  Shouldn't I be expecting something near of what CrystalDiskMark is reporting for Sequential writes?

  Version : Microsoft SQL Server 2017 (RTM-CU9-GDR) (KB4293805) - 14.0.3035.2 (X64) Jul 6 2018 18:24:36
  8 cores
  MaxMemory16gb RAM on a 32GB

  
BACKUP DATABASE StackOverflow2010 TO DISK = 'D:\Test\memory_increased.bak'


  Processed 1290536 pages for database 'StackOverflow2010', file 'StackOverflow2010' on file 1.
  Processed 2 pages for database 'StackOverflow2010', file 'StackOverflow2010_log' on file 1.
  BACKUP DATABASE successfully processed 1290538 pages in 109.257 seconds (92.280 MB/sec).

  Crystal Disk Mark
  -----------------------------------------------------------------------
  CrystalDiskMark 6.0.2 x64 (C) 2007-2018 hiyohiyo
           Crystal Dew World : https://crystalmark.info/
  -----------------------------------------------------------------------
  * MB/s = 1,000,000 bytes/s [SATA/600 = 600,000,000 bytes/s]
  * KB = 1000 bytes, KiB = 1024 bytes

   Sequential Read (Q= 32,T= 1) : 548.795 MB/s
  Sequential Write (Q= 32,T= 1) : 407.146 MB/s
  Random Read 4KiB (Q= 8,T= 8) : 392.375 MB/s [ 95794.7 IOPS]
  Random Write 4KiB (Q= 8,T= 8) : 197.563 MB/s [ 48233.2 IOPS]
  Random Read 4KiB (Q= 32,T= 1) : 244.675 MB/s [ 59735.1 IOPS]
  Random Write 4KiB (Q= 32,T= 1) :  91.468 MB/s [ 22331.1 IOPS]
  Random Read 4KiB (Q= 1,T= 1) :  33.350 MB/s [ 8142.1 IOPS]
  Random Write 4KiB (Q= 1,T= 1) :  89.909 MB/s [ 21950.4 IOPS]

  Test : 16384 MiB [D: 77.4% (180.0/232.7 GiB)] (x5) [Interval=5 sec]
  Date : 2019/01/09 8:03:11
    OS : Windows 10 Enterprise [10.0 Build 17134] (x64)

  Shouldn't I be getting around 400MB /s  while writting the backup to disk ?

  Thank you