SIOS DataKeeper primary and secondary systems have three types of volumes: system, non-mirrored and mirrored. During mirroring operations, system and non-mirrored volumes are not affected and the user has full access to all applications and data on these volumes.
What Volumes Cannot be Mirrored
The SIOS DataKeeper service filters out the following types of disk partitions:
- Windows system volume
- Volume(s) that contain the Windows pagefile
- Non-NTFS formatted volumes (e.g. FAT, FAT32, Raw FS, ReFS)
- Non-fixed drive types (e.g. CD-ROMs, diskettes)
- Target volumes that are smaller than the source volume
Volume Size Considerations
The source and target systems are not required to have drives of the same physical size. When the mirror is established, the target volume must be the same size, or larger than the source volume.
There is no limit on the size of volumes that can participate in a SIOS DataKeeper mirror. However, you should be aware that on initial mirror creation, all data that is in use by the file system on the source volume must be sent to the target. For instance, on a 20 GB volume with 2 GB used and 18 GB free, 2 GB of data must be synchronized to the target. The speed of the network connection between the two systems, along with the amount of data to be synchronized, dictates how long the initial mirror creation will take.