Snapshot size question

[bublik]

Hi,

I extracted this data from mgrClientBinMon.log file

 snapshot 'vmfs_11_Sch_SS_2.20' id=10243 read_only client_type='manager' length=500.0GB actual=10.5GB  

When it is reporting length... What does this mean, size of the actual volume or snapshot cannot grow beyond this size or something else?

Also I have thick provisioned volume:

Daily snapshot

  snapshot 'vmfs_09_Sch_SS_1.168' id=10127 read_only client_type='manager' length=750.0GB actual=1.02GB

Monthly

  snapshot 'vmfs_09_Sch_SS_3.5' id=8891 read_only client_type='manager' length=750.0GB actual=650.3GB

why would actual size be different for that much?

[bryan_hadzik]

Length is the reported size of the volume or snapshot. The largest it could grow to. Actual is the real amount of blocks changed in that snapshot.

The reason you can have such a large difference between the two is that most likely your monthly snapshot is the oldest snapshot. When using snapshots, the oldest snapshot contains almost all the data. the newer snapshots, and the volume itself, are only new data since the oldest snapshot.