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13 Dell EMC SC Series: Microsoft Exchange Server Best Practices | CML1037
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2.4.1 Archive mailboxes
Each mailbox in the database can have an archive mailbox. This allows users to have an archive repository
that does not impact existing mailbox quotas and allows them to retain data for longer periods of time. Archive
mailboxes can help eliminate PST files and keep information contained within Exchange Server. It is
important to note that an archive mailbox is a separate object from the user mailbox.
Beginning with Exchange 2010 Service Pack 1 (SP1), it is possible to provision a user's personal archive on
the same mailbox database as the user's primary mailbox, on another mailbox database on the same mailbox
server, or on a mailbox database on another mailbox server in the same Active Directory site. This feature
offers the flexibility to utilize SC Series tiered storage architecture to store archive mailboxes on a separate
volume utilizing a tier-3 RAID5 storage profile, putting this archive data on less expensive disks. Snapshots
can be taken much less frequently because this data changes less frequently.
Note: Archive mailboxes are only available while a user is online. They are not available if a user is running in
cached mode and is not connected to Exchange.
2.5 Online database maintenance
Database maintenance for Exchange 2013/2016/2019 has also been modified to work more efficiently. One of
these changes regards background database maintenance (BDM), which is now throttled back from 5 MB-
per-sec/copy to 1 MB-per-sec/copy.
In addition, the updates to ESE can reduce the cost of maintaining and managing a database. Database
maintenance is comprised of storage mailbox maintenance and ESE database maintenance.
2.5.1 Online defragmentation
Online defragmentation now runs 24x7 in the background by default. There are no configurable settings with
the default feature. Exchange monitors the database as it is being used and small changes are made over
time to keep it defragmented for space and contiguity. Online defragmentation is also throttled so that it does
not negatively impact client performance.
2.5.2 Online database scanning (checksumming)
The checksumming process can run in two different modes on the active database copies:
Default option: This has checksumming run in the background 24x7. This option is intended for most
databases which can require longer periods of time to complete a checksum. Exchange scans the full
database no more than once a day and will generate an alert if it does not finish scanning within seven days.
Second option: This runs as the last task in the custom-scheduled mailbox database maintenance process.
The amount of time it runs can be configured by altering the schedule calendar, which is recommended for
databases that are less than 500 GB in size. This allows these databases to finish scanning quickly, having
less impact to the continuous BDM process. The schedule can be modified in the database properties under
the maintenance section.
For more information, see technet.microsoft.com.