Microsoft Exchange System Attendant:

This article explains the characteristic features of the Microsoft exchange system attendant services. The Microsoft Exchange System Attendant service is primarily a collection of subcomponents that work together to proxy Active Directory requests and to regulate internal Exchange Server functions.

1.It is exchange related services. It is critical for exchange server’s performance and many exchange related services will not work.
2.You cannot mount the database unless the exchange system attendant service is running.
3.It facilitates AD communications to enforce the retention policies and mailbox quotas.
4.Main executable file is the MAD.EXE, located in Program Files\Exchsrvr\Bin folder and most of the subcomponents exist as .DLL files.

The following are the components of the System Attendant services.

DSACCESS Component:

1.DSACCESS.dll is used to prevent exchange server from flooding your exchange server with excessive requests.
2. In detail, When exchange server component such as exchange store or SMTP Transport engine needs to get the receipient information from AD, the query is routed through the DSACCESS component. Generally it acts as a proxy for these AD request. The recent request are stored in the cache to avoid the repetitive queries.

DSProxy Component:

1.DSProxy.dll acts as a proxy for AD queries coming from outlook clients.
2.In detail, when client running outlook 2000 or later, refers the GC for processing the AD query (such as a request to retrieve the GAL) in direct. Whereas the client older the outlook client 2000, will acts as a true proxy for communicating the GC, so DSProxy performs he operation on behalf of the client.
3.DSACCESS performs differently, DSACCESS proxies AD request coming from the other exchange component.

RUS – Recipeint Update Service:

1.Abv_dg.DLL is the core file for the RUS.
2.It is used for applying recipient policies to mail-enabled user objects.

Mailbox Manager Component:

The Mailbox Manager's job is to enforce policies that help to control the size of an information store, including mailbox quotas and message retention policies.

Server Monitor Component:

1.It is primarily used to keep exchange server’s link state information up to date.
2.The link state information is used to calculate the optimal path to various destinations within the exchange organization. Metrics like costs, availability and hop counts are taken into account.
3.It is responsible for monitoring server resources using WMI Windows Management Instrumentation.
4.It is also responsible for managing message tracking logs (if the message tracking is enabled).

Offline Address Book Generator:

1.The idea behind OAB generator (OABgen.dll) is for mobile users to access the address book, even is the users are offline.
2.So the offline users rely on the OAB instead of GAL.
3.The OABgen.dll file is stored in an Exchange public folder subfolder called Offline Address Book. This folder contains two subfolder: OAB Version2 and OAB Version 3a.

Free/busy Component:

1.The free/busy (madfb.dll) component is responsible for publishing the free busy information.
2.In detail, free busy information of other attendee is required for scheduling meeting. So the source user needs the free busy data of the target attendee’s calendar. Since user don’t generally have access to other user’s mailbox. Like OAB, the free/busy(madfb.dll) component is stored in a subfolder of the system public folder named SCHEDULE + FREE BUSY.
3.When a user creates an appointment or meeting, the exchange store sends the corresponding free/busy information to the exchange system attendant mailbox. The madfb.dll extracts the free busy data from the message and publishes it in the SCHEDULE + FREE BUSY folder.

Metabase Update Service:

1.Metabase Update Service (ds2mb.dll) is closely related to the IIS.
2.IIS metabase is the core file for IIS. Given that, exchange is dependent on IIS, exchange is also dependent on the IIS metabase.
3.IIS metabase exists in the form of an XML file named Metabase.xml, also stores as binary file called Metabase.bin (located in System root\system32\inetsrv) and the corresponding schema file called MBSchema.xml.
4.Some Exchange configuration information related to SMTP Virtual servers, the HTTP configuration of OWA and few others are stored in AD, but are needed by IIS. This is where the Metabase Update Service comes into play. This service replicates protocol related exchange server configuration information from the AD to the IIS metabase.

Hope the above is informative. Please ping me if you have any questions.

Thanks

Logu

logu_microsft@hotmail.com
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