Hi Experts,
Though WITH_CHECKSUM" option is suggested while doing the backups, but if using "NO_CHECKSUM" makes any difference in backup SIZE. Please share with thoughts.
Technology Tips and News
Hi Experts,
Though WITH_CHECKSUM" option is suggested while doing the backups, but if using "NO_CHECKSUM" makes any difference in backup SIZE. Please share with thoughts.
Why not testing it?
No checksup only checks pages when they are backed up or when they are read from disk into memory. The consistency check is limited. Apart from that I am not aware it does any more task. This would not add any data whatsoever so NO it is not going to affect the backupHi Experts,
Though WITH_CHECKSUM" option is suggested while doing the backups, but if using "NO_CHECKSUM" makes any difference in backup SIZE. Please share with thoughts.
No, it does not affect a size of the backup
/*
When the WITH CHECKSUM option is used for a backup, the backup process will test the page checksums that exist on the data file pages being backed up. If a bad page checksum is found, the backup process will stop (by default you can override this using WITH CONTINUE_AFTER_ERROR but Id only do that in an emergency). So if the backup completes successfully, you know that there are no broken page checksums.
*/
Dear Stefan
Thanks for your reply.
I actually checked the backup of two databases with both options [with checksum and with no_checksum(defualt)] but found exactly the same size of the backups. (size of backups was over 1GB)
As the following doc says
https://msdn.microsoft.com/en-us/library/ms186865.aspx
Specifies that the backup operation will verify each page for checksum and torn page, if enabled and available, and generate a checksum for the entire backup.
does this checksum information is the part of backup itself, if yes, it is so tiny that it will not impact the size? This raises the question which I put here in the forum.
regards
khalil
does this checksum information is the part of backup itself, if yes, it is so tiny that it will not impact the size? This raises the question which I put here in the forum.
When you enable backup with checksum option all pages which wuld read from disk for backup would be checked and this is what BOL doc says. Yes checksum is part of backup and would only be considered with this backup.
Again it just checks consistency of page read from disk this is all it does.
No checksum only checks pages when they are backed up or when they are read from disk into memory. The consistency check is limited. Apart from that I am not aware it does any more task. This would not add any data whatsoever so NO it is not going to affect the backupHi Experts,
Though WITH_CHECKSUM" option is suggested while doing the backups, but if using "NO_CHECKSUM" makes any difference in backup SIZE. Please share with thoughts.
The text you quoted say that CHECKSUM does *two* things:
1. Check each page checksum, and it will error if it fines any that isn't correct. This is a check and generates nothing that would be stored anywhere.
2. Calculate a checksum over the entire content of the backup. This is written in the header and is indeed so tiny so it doesn't impact backup size.
The text you quoted say that CHECKSUM does *two* things:
1. Check each page checksum, and it will error if it fines any that isn't correct. This is a check and generates nothing that would be stored anywhere.
2. Calculate a checksum over the entire content of the backup. This is written in the header and is indeed so tiny so it doesn't impact backup