What percent of NAS data is backed up to tape?
I don't think anyone really knows what the exact percentage is, but I've heard that less than half of NAS is backed up at all -- primarily because most NAS devices exist in workgroup or departmental environments and they are not very orthodox about performing backups. Of those that are backed up, most are backed up to tape. Things are changing, however. Network Appliance released the NearStore product with SnapVault software to serve as disk-to-disk backup for NAS devices. Subsequently, data on the NearStore product may be backed up to tape. This follows the overall trend in block storage environments to use a disk-to-disk approach for backup and then take the secondary copy as the source for the tape backup. What we have here is a decoupling of the backup for restoration purpose and the archival for disaster protection purpose. By doing disk-to-disk backup, you can greatly improve the restore time, and you can also take more backups that are based on a recovery point objective. The business requirements for creating the tape copy that can be removed can operate on a totally different schedule. We'll see more disk-to-disk backup solutions and more environments where the tape backup is independent of this action.
The value of quick restores varies but it's still very important to companies. It can actually justify the added cost of the extra disk in your storage environment. That, coupled with continued price declines in disk, a cheaper version of disk storage (albeit with less performance), and the advent of ATA-based storage systems and we have an even easier justification for the move to disk-to-disk backup solutions. This doesn't remove the need for tape but it does change the process based on differing business requirements now.
The bottom line is that we'll continue to see more disk-to-disk backup solutions and fewer disk-to-tape backups. Overall, maybe fewer tape drives will be needed, but the business requirements for tape will, in most cases, still exist.
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This was first published in November 2003