Technical information on how data is stored - may be used when preparing Data Management Plans or Data Privacy Assessments
FMRIB and OHBA's file stores use the ZFS file system to store data. This is a check-summed copy-on-write file system that verifies data blocks whenever they are accessed (and on a regular schedule for rarely accessed files). Data is distributed over multiple disks with sufficient parity data to ensure that disk failures do not cause data loss. Any data failing checksum are, where possible, automatically repaired or the corruption of the file is notified to an administrator, so minimising the likelihood of silent data rot. The copy-on-write method of operation ensures that the file system always remains in a consistent state.
/home/fs0, /vols/Data and /ohba/* folders are located in triple-disk redundant data stores. This allows the system to survive up to three disk failures in any one set of disks (there is more than one set). This level of data security comes at the cost of lower overall performance, especially with respect to cluster tasks. To aid performance, SSD based storage is used to improve write performance.
/vols/Scratch is located on a mirror-pair redundant data store. The mirror pair allows survival from loss of one of the disks in each pair (of which there are many). This means it is less secure against hardware failure than the other stores, but the performance is much higher with respect to multiple computers accessing the store at once (e.g. the cluster). The speed increase is however traded for overall capacity, so this share is smaller than /vols/Data store.
/vols/Data and /vols/Scratch are shared from high-availability servers allowing some system maintenance tasks to take place with minimal disruption to service.
/vols/Scratch and /ohba/* folders utilise at-rest encryption to ensure that data from failed disks is not recoverable.