The CH3SNAS uses the Linux ext2 file system, and thus cannot preserve data which was written to the hard disks (e.g. using Microsoft Windows) before these are inserted into the CH3SNAS: reformatting will normally be necessary for both a new and a used hard disk. Lets assume the drives have storage capacities of respectively C1 and, if a 2nd drive is present, C2 Gigabytes. The CH3SNAS supports a number of different ways in which to format individual hard disk partitions using the built-in web interface:
- Standard – each drive can be accessed as a different volume (results in a volume of size C1 and, if present, C2)
- JBOD – Just-a-Bunch of Disks, allowing both drives to be accessed as a single large volume (of size C1+C2)
- RAID 0 – files are “striped” over both drives, thus potentially giving higher performance (resulting in a single volume of size 2*min(C1,C2))
- RAID 1 – files are automatically mirrored at the sector level on both drives, thus allowing data recovery if either drive fails. RAID 1 results in a single volume of size min(C1,C2). Note that this occupies 2*min(C1,C2) of total disk space.
Configurations 2, 3, and 4 require a dual-drive system. A RAID 0 or 1 volume can be no larger than the smallest of the two drives, but can optionally be configured to be smaller than min(C1,C2). Any remaining space on both drives becomes accessible as a single JBOD volume.
Consequently, a dual-drive system can support up to 6 alternative configuration options:
- Two Standard volumes
- A single large JBOD volume
- A single RAID 0 volume (if both drives have the same size, and no JBOD volume is needed)
- A single smaller RAID 1 volume (if both drives have the same size, and no JBOD volume is needed)
- A RAID 0 volume and a JBOD volume
- A RAID 1 volume and a JBOD volume (see screen shot)
It may be possible to create other working configurations (such as RAID 0 + RAID 1 + JBOD), but these cannot be created using the built-in configuration interface and will probably not have been tested.
Under Windows, volumes can be assigned user-selectable drive letters (such as R: for a RAID).