February 26, 2015 at 6:23 am
HI,
when I run
select s.database_name, s.name, s.backup_start_date, s.backup_size, s.type from backupset s join backupmediafamily f on
s.media_set_id = f.media_set_id
where s.database_name = 'AdventureWorks' and type = 'L' order by backup_start_date desc
I get backup_size in the result = 367616 ( it's in bytes, according to BOL)
But in the window .trn file it shows = 388 KB
I think 1 KB = 1000 bytes So, when I do 367616/1000 = 367.616 KB which is different than 388KB!!!!!
February 26, 2015 at 7:56 am
It's actually 1024, not 1000. That equates to 359kb. Probably what's not included is header information and meta-data about the backup itself. That would explain the extra 19kb.
"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt
Author of:
SQL Server Execution Plans
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February 26, 2015 at 9:15 am
Grant, that's what I thought. I just googled it says 1 Kilobyte = 1000 byte. Backup_set is in bytes according to BOL. I am trying to figure out backups size everyday to adjust a drive but numbers don't match!!!
February 26, 2015 at 11:27 am
Clearly clarity and computer science don't always go hand in hand.
I'm pretty sure using the query should get you ballpark close. It won't be perfect. I'm pretty sure the value stored is the data moved into backup, not including header information. But the header info is going to be only a little off... Oh, and that data moved probably doesn't include rolled forward or rolled back transactions.
"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt
Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning
March 2, 2015 at 8:10 am
Thank you very much!!!
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