We recommend that write caching be disabled on the drive hosting the Active Directory database. Without caching, SSDs suffer significantly higher performance degradation than HDDs.
However, the best performance for the EXACT database can be achieved on SSDs.
Therefore it is recommended that the server operating system be installed on a separate hard disk drive and the EXACT database on one or more SSDs.

These steps guide the selection of drives for the EXACT server computer.

Choosing the drive technology

• HDD technology is supported. One hard drive is a minimum for EXACT to run
• HDD is recommended for the OS drive (due to Active Directory mentioned above)
• SSD is recommended for the EXACT database (and Images, if (optionally if using imaging software)
• RAID is highly recommended for the SSDs

Please refer to your IT/Hardware provider for recommendations on the Resilience and performance of drives installed on your machines.

• Standard: RAID 1: two mirrored disks.
• Recommended: RAID 5: At least three disks striped with parity.

Calculating the size

The capacity of the chosen drive(s) needs to cater for:

• Operating System
• Database (read-write, random access, read often, writes to anywhere on the disk)
• Images (write once and read often, writes sequentially)

Estimating the growth capacity

As every practice installation is unique, the growth capacity needs to be individually estimated.

Each disk must cater for its own 5 year growth capacity (5 years is the typical lifespan of the hardware before replacement), depending on the function of the disk and the anticipated growth of the business.

In general, the Operating System remains relatively stable in size, the Database increases slowly and the Images storage can increase quickly

Deciding on the disk configuration

These calculation examples are for demonstration purposes only.

Capacity

Server Disk options