A method comprising: identifying a data object, wherein the data object comprises data segments to be backed up during a backup process, and the data object is identified, in a cache of a client system, as being stored at a deduplication server; characterised by the steps of protecting the data object and the data segments stored at the deduplication server from being deleted from the deduplication server during the backup process by sending, by the client system, a request to the deduplication server, wherein the request comprises a request for the deduplication server to add a task identifier to the data object stored at the deduplication server, the request comprises a reference to the data object, and addition of the task identifier to the data object indicates to the deduplication server that the data object and the data segments stored at the deduplication server are not to be deleted from the deduplication server; and in response to a determination that the deduplication server has successfully added the task identifier to the data object stored at the deduplication server, adding (555, 640), by the client system, an active identifier to each of the data segments stored in the cache, wherein addition of the active identifier to the each of the data segments indicates to the client system that the each of the data segments will not be deleted from the deduplication server during the backup process. identifying a data object, wherein the data object comprises data segments to be backed up during a backup process, and the data object is identified, in a cache of a client system, as being stored at a deduplication server; characterised by the steps of protecting the data object and the data segments stored at the deduplication server from being deleted from the deduplication server during the backup process by sending, by the client system, a request to the deduplication server, wherein the request comprises a request for the deduplication server to add a task identifier to the data object stored at the deduplication server, the request comprises a reference to the data object, and addition of the task identifier to the data object indicates to the deduplication server that the data object and the data segments stored at the deduplication server are not to be deleted from the deduplication server; and the data object comprises data segments to be backed up during a backup process, and the data object is identified, in a cache of a client system, as being stored at a deduplication server; characterised by the steps of protecting the data object and the data segments stored at the deduplication server from being deleted from the deduplication server during the backup process by sending, by the client system, a request to the deduplication server, wherein the request comprises a request for the deduplication server to add a task identifier to the data object stored at the deduplication server, the request comprises a reference to the data object, and addition of the task identifier to the data object indicates to the deduplication server that the data object and the data segments stored at the deduplication server are not to be deleted from the deduplication server; and in response to a determination that the deduplication server has successfully added the task identifier to the data object stored at the deduplication server, adding (555, 640), by the client system, an active identifier to each of the data segments stored in the cache, wherein addition of the active identifier to the each of the data segments indicates to the client system that the each of the data segments will not be deleted from the deduplication server during the backup process. added the task identifier to the data object stored at the deduplication server, adding (555, 640), by the client system, an active identifier to each of the data segments stored in the cache, wherein addition of the active identifier to the each of the data segments indicates to the client system that the each of the data segments will not be deleted from the deduplication server during the backup process.