Storage Groups and Mailbox Databases in Exchange Server 2003/2007/2010

Here in this post, we are discussing the Storage Groups and Mailbox Database in Exchange Server 2003/2007/2010

In exchanging 5.5 there are 3 databases to support the Email container and the message flow

• PRIV.EDB – responsible for Mailbox Databases
• PUB.EDB – Responsible for Public folder databases
• DIR.EDB – Stores the own directory structure for exchange.

This DIR directory no longer exists in higher version like exchange 2000, exchange 2003 and exchange 2007. We have only 2 database files, one for Mailbox Database (PRIV.EDB) and other for Public Folder Database (PUB.EDB). File extension with .STM is nothing but a database file to support the Non MAPI clients to access their mailbox contents.

If these database grow in size it’s very complicated in backup and restoring process. Here the storage group evolves into action.

Storage Groups and Databases

Storage groups are nothing but the Structural unit that holds the databases. If we deeply look into the storage groups, these storage groups are nothing but the folders to separate the database file. If we choose Enterprise Edition, we can create

Exchange Server 2010

Storage Groups concepts are removed in Exchange Server 2010 and there is no need to create a Recovery Storage Group in disaster recovery scenario. Instead of RSG, we can create a Recovery Mailbox Database. We can create 100 Databases in Enterprise Edition

Exchange Server 2007

50 storage group / 5 Database in single storage group – Maximum of 50 Database, Recommended having 1 database per storage group if we are deploying LCR, CCR or SCR

Exchange Server 2003

4 Storage Groups / 5 Database in single Storage group – Mailbox database and Public Folder Database can be combined

If we choose Standard Edition, We can create

Exchange Server 2010

Storage Groups concepts are removed in Exchange Server 2010 and there is no need to create a Recovery Storage Group in disaster recovery scenario. Instead of RSG, we can create a Recovery Mailbox Database. We can have 5 Databases in Standard Edition

Exchange Server 2007

5 storage group / 5 Database in single storage group – Maximum of 50 Database, Recommended having 1 database per storage group

Exchange Server 2003

1 storage group / 2 Database in single storage group – In which contain 1 Mailbox Database and 1 Public Folder Database

What happen if mails come into exchange server?

Once the mail comes into the exchange server it writes the mails as transactional logs and also the same in system memory simultaneously. What the transactional log will do in the sense, it will hold the mails for a while until the mailbox database is freed up. The transactional logs are 1 MB in size and if the mail comes with size of 5 MB, the transaction log will first write the 1Mb log and creates a another transactional log, it will write the log files until the mails have completed.

File types in exchange server

In which Exchange Server 2007 holds the following files, in the following location

Streaming Database with the extension .stm is removed in Exchange Server 2007

When we are looking into Exchange Server 2003, under the following location

These are the files exists in Exchange Server 2003 with the following extensions.

.CHK – check point file, keeps track of which transactional logs moves into database files. Keep on check the log file entering the database in a current order

.LOG – 2 types of transactional logs –

1. Current Transactional log – eoo.log file which write the current transactions into transactional logs. If it reaches 1 MB, it will rename the log file into E00000001.log

2. Transactional log – If Current Transactional log reaches 1 MB, it will rename the log file into E00000001.log

.EDB – Stores the database files

Temp.EDB – Temporary database file, which will process the transactional logs that are to be to write in .EDB Database file

.JRS – Reserved Log files – if the size of the disk is full and you can’t write any mails as transactional logs these files will help into action

Storage Group Management

Options to go for storage Management

1. Direct attached Storage
2. Storage Area Network
3. I SCSI

NOTE: Network attached storage will not be supported in Exchange Server 2007

Following shows the good storage options in order to have high availability. its good separate the following files in different disks in order to have better Performance. Reliability and Recoverability

Operating System: System files to be backed up. RAID 0 or RAID1

Database Files: if we move the database to different disk and if you are making backup the transactional logs will be added into the Backup. Provides better recoverability, RAID5 (Stripe set with Parity)

Transactional Log Files: in order to handle load, it’s good to have Transactional log files in different disk. If both the log file and database file are in same disk, increase performance and reliability. RAID1 (Mirroring)