Other problems not unique to Linux

One important problem is that there is no API between users of a device and its driver. The size of the TSS device is not fixed but varies dynamically as the organization of data changes among different storage personalities. If there exists a file system that can talk to underlying device through an appropriate interface and can dynamically change the file system size, this feature of dynamic growth or shrinking feature of TSS can be exploited. None of the file systems available on Linux platform have such a facility (and most other FS on most OSes too!), so we still need to export a fixed size of the device (required at time of mount). During device configuration, the user needs to specify the fraction of device that can be under RAID1 and fraction that will be compressed. Using this information the device size is calculated and exported. Ambiguity still exists as the amount of compression achieved cannot be predicted in advance.