Avatar of keithdarl
 asked on

Exchange Storage


Can I ask the following question,
If a user sends a mail with 1Mb attachements to say 50 users within the same Exchange organisation.
Will the resulting increase in IS storage be 50Mb (ie 1Mb added for each of the 50 inboxes that received the email)?
1Mb, ie does exchange store it once and have pointers to the 50 inboxes?


Avatar of undefined
Last Comment

8/22/2022 - Mon

Which version of Exchange are you using?

Exchange 2003 and 2007 use single instance storage, meaning that the attachement will be stored once.

Exchange 2010 no longer uses single instancing meaning you will end up with a 50MB increase in the store. http://blogs.technet.com/b/exchange/archive/2010/02/22/3409361.aspx

Also, single instancing was only ever for users within the same mailbox store (as in, per database) rather than the same Exchange org.

Log in or sign up to see answer
Become an EE member today7-DAY FREE TRIAL
Members can start a 7-Day Free trial then enjoy unlimited access to the platform
Sign up - Free for 7 days
Learn why we charge membership fees
We get it - no one likes a content blocker. Take one extra minute and find out why we block content.
Not exactly the question you had in mind?
Sign up for an EE membership and get your own personalized solution. With an EE membership, you can ask unlimited troubleshooting, research, or opinion questions.
ask a question

Not even an assist despite answering the question, providing Microsoft's statement and reasoning behind it and expanding to clarify SIS with regards to the whole exchange org :(
Experts Exchange has (a) saved my job multiple times, (b) saved me hours, days, and even weeks of work, and often (c) makes me look like a superhero! This place is MAGIC!
Walt Forbes


Thanks for your answers above, just to clarify, the threads below from the Microsoft forum provide better insight:



here's a quote from this one:
     ' In Exchange 2010, the store schema has changed so that all data in a mailbox have stored-in tables close to each other in the database. Actually, each mailbox has its own folder, message header, body, and its own view table. So, the concept of single instance storage no longer exists when it comes to Exchange databases. A side effect of removing SIS from Exchange was that a database was bloated by approximately 20%. Exchange PG found a solution to this by compressing the databases (more specifically message headers and text/HTML bodies). By giving each mailbox its own set of tables, most I/Os performed against a DB are now mostly sequential I/Os. '

This one has a good explanation , though it's not from Microsoft: