Business Copy EVA and Exchange PST files

[Monica Peck]

Regarding Business Copy EVA Snapshots , it seems that the copy-on-write happens at the “block” level and not the file level. With Exchange 2003, if users store their PST files on the SAN and a snapshot is created of those PST files, please confirm that only the blocks within the file are copied out if the user adds new emails to their PST file.

Thank you.

[Mike Reznak]

Hi,
BC Snapshot is block level operation. It transfers only the changed blocks. All unchanged blocks on snapshot are read from primary disk.

Mike

[Monica Peck]

So would you AGREE that the entire PST file would NOT be copied out if just a few additional emails are stored in an exiting (much larger) PST file consisting of several hundred emails, and a snapshot was created of that PST file?

Thank you.

[Uwe Zessin · Accepted solution]

Correct. The EVA only serves blocks of data and does not know what a file is. The data can be user data or filesystem metadata or database metadata or or or... The snapshot does not know what's in the 'segment' where a block is changed (the granularity for copy-on-write is a bit higher than a single 512 byte block).