Backup size

  • hello experts,

    i have taken a backup of database, backup size around 112 gb, when i archived it as a .RAR file it reduced upto 5.5 GB only, how did it happen, i have a doubt tht is archived correctly or not? if it is archived correctly how can it reduced upto that much level??

  • Did you do a compressed back up or a normal back up?

    -Roy

  • i have done a normal backup

  • Take a compressed backup. It will almost be the same size as that of the .RAR file. When you take a normal back up, the data is not compressed. The RAR compression and SQL compression will be able to compress this. Also depending on the data you have in your database, compression ratio might change. For instance string data will get more compression than ints (As far as I know).

    -Roy

  • i cant take compressed backup, using 2005.

  • I thought you were using SQL 2008 since the question is in the SQL 2008 forum. The normal back ups does not compress the data. Therefore RAR file can compress it. If you want to see if the file that got compressed is still valid, do a restore of the header and see if it is good.

    -Roy

  • sachinsoni84 (10/13/2010)


    i have taken a backup of database, backup size around 112 gb, when i archived it as a .RAR file it reduced upto 5.5 GB only, how did it happen, i have a doubt tht is archived correctly or not? if it is archived correctly how can it reduced upto that much level??

    Uncompressed database data tends to compress very well - there's usually a lot of blank space and repeated values, for example.

    You should always verify your backups, ideally by uncompressing them and restoring them to a second server, and then checking the contents.

  • ohh i placed question in 2008 forum, sorry

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