Blobpages Do Not Pass Through Shared Memory

Blobpages store large amounts of data. Consequently, the database server does not create or access blobpages by way of the shared-memory buffer pool, and it does not write blobpages to either the logical or physical logs.

If blobpage data passed through the shared-memory pool, it has the potential to dilute the effectiveness of the pool by driving out index pages and data pages. Instead, blobpage data is written directly to disk when it is created.

To reduce logical-log and physical-log traffic, the database server writes blobpages from magnetic media to dbspace backup tapes and logical-log backup tapes in a different way than it writes dbspace pages. For a description of how dbspaces are logged, refer to Dbspace Logging.