No Single Instance Storage (SIS) In Exchange 2010…

The store schema in 2010 has been given a big change and as a result of the new store architecture, Exchange 2010 no longer supports Single Instance Storage (SIS). This means that when you send a 1mb attachment to 50 users within the same database, the size of the database will grow by 50mb. In…

The store schema in 2010 has been given a big change and as a result of the new store architecture, Exchange 2010 no longer supports Single Instance Storage (SIS). This means that when you send a 1mb attachment to 50 users within the same database, the size of the database will grow by 50mb. In previous versions of exchange, the attachment is only stored once and all recipients get a pointer to the actual attachment from which it opens. Hence the database only increases in size by 1mb.

With the removal of SIS from 2010, the exchange product group estimates an increase in database size of upto 20%. This has to be considered when designing a 2010 environment. As the Extensible Storage Engine (ESE) is optimized for handling large (10Gb+) mailboxes in 2010, the 20% increase in storage is not a big deal considering that you don’t need expensive RAID solutions if you have a DAG with 3+ copies of your database. Plus the hard drives are getting bigger and cheaper these days!

9 Comments

  1. Lars Berntrop says:

    Or you could migrate to Domino 8.5.3 and enjoy DAOS (SIS like feature) across the entire SERVER instead of just one DB. So ANY attachment duplicated in say 6000 mail databases will be stored only once…

    1. Rajith Enchiparambil says:

      Thanks Lars ;)

  2. Rajith Jose Enchiparambil says:

    Duplication of data will be there in Exchange 2010 as there is no SIS. There are no tools to avoid it. It is just the way Exchange 2010 works.

  3. Anonymous says:

    Hi Rajith,
    Is there any tools available for deduplication. As there is no SIS in exchange 2010.

  4. Anonymous says:

    my exchange database is 150gb. shoot me before they come for me.

  5. Rajith Jose Enchiparambil says:

    Yes Mdrooij. SIS only comes into play for recipients in the same database. I should have been more clear, will amend my article.

  6. Rajith Jose Enchiparambil says:

    These changes make sense now as the storage are getting bigger and cheaper. Plus the size of the mailboxes are growing as well and hence to have a common table structure for all mailboxes just for SIS is not suitable in modern networks.

  7. Not quiet .. SIS was only effective within the same database. Also, Exchange 2010 introduces mail compression (headers, body, not attachment, but that should not be a problem as most attachments (zip, docx) are compressed). Check out my article here: http://tinyurl.com/yb6a886

  8. Paul Cunningham says:

    Hi Rajith, the critics really jumped on this SIS issue with gusto but they mostly missed the point of the changes.

    SIS was become less effective and the database performance improvements under the new schema are a bigger advantage anyway.

    I wrote a post about it a few months ago too:
    http://bit.ly/8b64X5

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