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Optimizing your backup – Tips and Tricks

Last week at the TechCon2013, sponsored by the SQLBangalore User Group and other User Groups in Bangalore, I did a talk on how to optimize your backup/restore. I focused on the three main aspects of Backup/Restore and talked about some of the things which can be done to optimize them

  1. Read from Disk
  2. Store in Memory
  3. Write to Disk/Tape

For the Demos, I used 3 databases as described.

Database 1

  • Size – 12 GB
  • DB Name – AdventureWorks2012SingleFile
  • Number of Data Files: 1
  • Disk Allocation Size: 4KB

Database 2

  • Size – 12 GB
  • DB Name – AdventureWorks2012MultiFile
  • Number of Data Files: 4 (spread on 4 different physical disk)
  • Disk Allocation Size: 64KB

Database 3

  • Size – 4 GB
  • DB Name – AnotherSingleFileDatabase
  • Number of Data Files: 1
  • Disk Allocation Size: 64KB

The slide deck for the presentation is included below.

Optimizing Reads

To optimize reads, I focused mainly on the following

  1. Reading from a single MDF file vs. reading from multiple Data files
  2. Using higher disk allocation unit, I would be writing another post on effect of disk allocation unit size to SQL backup.

All backups were performed to a Null device. The idea was to test the read performance. I saw the following backup performance for the databases mentioned above.

   1:  

   2: backup database [AdventureWorks2012SingleFile]

   3: to disk = 'NUL' WITH COPY_ONLY

   4: --BACKUP DATABASE successfully processed 1521753 pages in 26.510 seconds (448.460 MB/sec).

   5:  

   6: backup database [AnotherSingleFileDatabase]

   7: to disk = 'NUL' WITH COPY_ONLY

   8: --BACKUP DATABASE successfully processed 569482 pages in 9.202 seconds (483.489 MB/sec).

   9:  

  10: backup database [AdventureWorks2012MultiFile]

  11: to disk = 'NUL' WITH COPY_ONLY

  12: --BACKUP DATABASE successfully processed 1599457 pages in 25.244 seconds (494.998 MB/sec).

I get better performance with later disk allocation sizes and multiple sizes.

Optimizing Writes

To optimize reads, I focused mainly on the following

  1. Writing to a single backup file vs. writing to multiple backup files
  2. Using Compression
  3. Changing the MaxTransferSize option for the backups.

All backups were performed to a 4K allocation unit drive, except for the multiple file backup, which were performed on a 64K Allocation unit disk. The following backup performance was observed.

   1: backup database [AnotherSingleFileDatabase]

   2: to disk = 'C:\AnotherSingleFileDatabase.bak'

   3: Go

   4: --BACKUP DATABASE successfully processed 569493 pages in 52.510 seconds (84.729 MB/sec).

   5:  

   6: -- Delete the file to preserve Space

   7: xp_cmdshell 'del C:\AnotherSingleFileDatabase.bak'

   8: -- Backup taken to Multiple Files on Different drives of 64K disk allocation Units

   9: backup database [AnotherSingleFileDatabase]

  10: to 

  11: disk = 'F:\AnotherSingleFileDatabase_BackupFile1.bak',

  12: disk = 'G:\AnotherSingleFileDatabase_BackupFile1.bak',

  13: disk = 'H:\AnotherSingleFileDatabase_BackupFile1.bak',

  14: disk = 'E:\AnotherSingleFileDatabase_BackupFile1.bak'

  15: Go

  16: --BACKUP DATABASE successfully processed 569490 pages in 33.600 seconds (132.414 MB/sec).

  17: --- Delete all the files

  18: xp_cmdshell 'del E:\AnotherSingleFileDatabase_BackupFile1.bak'

  19: go

  20: xp_cmdshell 'del H:\AnotherSingleFileDatabase_BackupFile1.bak'

  21: go

  22: xp_cmdshell 'del G:\AnotherSingleFileDatabase_BackupFile1.bak'

  23: go

  24: xp_cmdshell 'del F:\AnotherSingleFileDatabase_BackupFile1.bak'

  25: go

  26:  

  27: -- Backup With COMPRESSION

  28: backup database [AnotherSingleFileDatabase]

  29: to disk = 'C:\AnotherSingleFileDatabase.bak'

  30: WITH COMPRESSION

  31: Go

  32: ---BACKUP DATABASE successfully processed 569491 pages in 25.721 seconds (172.977 MB/sec).

  33: xp_cmdshell 'del C:\AnotherSingleFileDatabase.bak'

  34: Go

  35:  

  36: -- MAXTRANSFER OPTION

  37: DBCC TRACEON(3605,3213,-1)

  38: -- Writes backup Configuration related informtion to the trace file.

  39:  

  40: backup database [AnotherSingleFileDatabase]

  41: to disk = 'C:\AnotherSingleFileDatabase.bak'

  42: WITH COMPRESSION

  43: go

  44: xp_cmdshell 'del C:\AnotherSingleFileDatabase.bak'

  45: Go

  46: sp_readerrorlog

  47: go

  48:  

  49: backup database [AnotherSingleFileDatabase]

  50: to disk = 'C:\AnotherSingleFileDatabase.bak'

  51: WITH COMPRESSION, MAXTRANSFERSIZE = 2097152

  52: Go

  53: -- BACKUP DATABASE successfully processed 569490 pages in 21.920 seconds (202.971 MB/sec).

  54: xp_cmdshell 'del C:\AnotherSingleFileDatabase.bak'

  55: Go

We got better write performance when using a 64K allocation unit disk and when using Multiple Files. Further performance improvement was observed with Compression and by increasing the MaxTransferSize for the backups.

Optimizing Memory

To optimize reads, I focused mainly on changing the BufferCount option for the backups. This would help create more buffers in the memory for the buffer.

Total Memory used = BufferCount * MaxTransferSize

While i did not have a demo for the performance improvement when increasing the number of buffer, I had a demo on the side affect of increasing the BufferCount/MaxTransferSize to be very high.

   1: backup database [AnotherSingleFileDatabase]

   2: to disk = 'C:\AnotherSingleFileDatabase.bak'

   3: WITH COMPRESSION, MAXTRANSFERSIZE = 2097152, BUFFERCOUNT = 3000

   4: Go

   5: -- Error Message

   6: --There is insufficient system memory in resource pool 'default' to run this query.

If we increase the BufferCount and the MaxTransferSize to be very high, we would get into memory issues on the server.

Hopefully this information helps.

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