Please tell me if this nandroid backup is okay

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http://forum.xda-developers.com – The actual backup folder (the folder which name is the date the backup was created) size is 17mb. while the "blobs" folder located on the clockworck mod folder is 929mb... is this normal ? PD: in fact, i have other nandroids stored on my pc which the backup folder is like 700mb-1gb, and there is no "blobs" folder. (HowTos)