So Many Bytes, So Little Time

Good thing disk-to-disk-to-tape (D2D2T) backup solutions are coming to the rescue--and not a minute too soon.

The idea behind D2D2T is to back up from production disk to backup disk as quickly as possible. Once this "D2D" has finished, files can be backed up or migrated to tape at a more leisurely pace. Most D2D2T hardware is pretty impressive (1 TB to 2 TB of disk and tape is standard), but the real key to the success of this new technology is software. Finding a file in a 4-TB haystack can be frustrating if you're working with poor D2D2T backup/restore/migration software.

Clever Connectivity Solutions
To move lots of bytes to D2D2T devices in a short time, you need a big data pipe, but that's not enough. Locally attached SCSI backup devices aren't the answer because they're generally limited to backing up one computer at a time. In addition, they usually can use no more than a modest portion of SCSI bandwidth due to disk and other bottlenecks.

The solution is for multiple computers (clients) to simultaneously push data to D2D2T devices over a high-bandwidth link. Links include 1-Gbps Gigabit Ethernet and 2-Gbps Fibre Channel. Protocols now in use or soon to come into play include iSCSI, SCSI over Fibre Channel Protocol (SCSI-FCP) and Remote Procedure Calls (RPC).

All of these protocols allow a client computer to see the D2D2T unit as a backup device. iSCSI and SCSI-FCP solutions are backup-software agnostic. You can use them with any software that can back up to disk. Some devices add tape-drive and even tape-autoloader emulation, significantly enhancing your backup options.

D2D2T is new, and only a few units are available. In this review, I focus on two of the earliest and highest capacity arrivers: Louisville, Colo.-based Breece Hill's iStoRA 4000 and San Diego-based Overland Storage's REO R2000. For purposes of this review, I connected both products to a Gigabit Ethernet network. During tests, I found technical support from both companies to be excellent.

Click here for a review of a smaller-scale D2D2T device, the easy-to-use Certance CP 3100. The product is a terrific option for clients that have modest needs, offering full D2D2T functionality in a small footprint at an affordable price.

Breece Hill iStoRA 4000
The iStoRA, a 4U rackmount unit, includes a complete Windows XP PC. The unit had six 250-GB SATA hard drives, an LTO 2 (200 GB per tape) tape drive with a 10-slot auto changer, as well as dual-power supplies. Two of the drives are mirrored (RAID 1) and contain the operating system and metadata used by Avail Solutions' Integrity backup/restore/ migration software. You can also use remaining space on the mirrored RAID drives to store mission-critical data. The four other drives are for backups and can be used singly or configured as RAID 1 or RAID 5.

You use Avail's Integrity Vault Administrator software to manage what are called "storage vaults," which represent specific disk and tape devices installed on the iStoRA. The vault-management software is easy to use once you understand its terminology.

The Integrity backup/restore/migration software runs on client computers and, like the vault-management software, is easy to use once you understand the overall configuration of iStoRA devices. The view of the iStoRA and its vaults from a client running Integrity is totally transparent and is based on an RPC-over-IP link between the client and the iStoRA.

You can run jobs in real-time or schedule them. Jobs reside on iStoRA disk and tape and are easy to find when it's time for a restore. You can run restores from the iStoRA or the client. In addition, you are given the ability to prevent a client from running the restore application.

The iStoRA can back up Windows, Solaris, Linux, BSD Unix and Mac OS clients. There are no agents to support specific applications with open databases, such as SQL Server, Oracle, SAP and Exchange Server. Instead, you use pre-backup and post-backup commands to shut down the applications and free up databases for backup.

Overland Storage REO R2000
The REO R2000 2U rackmount unit I tested included dual-power supplies, eight 250-GB SATA drives (configurable as RAID 0 or RAID 5), one 10/100 Ethernet management port, and two Gigabit Ethernet data ports. The REO R2000 is managed by using a cleverly accessed Web interface. Just map a drive to the R2000, then run an HTML management application from the drive.

The application can also be used to set Gigabit Ethernet port IP addresses and for creating links between iSCSI client computers and the R2000. The R2000 runs on Linux, but only supports OSes with iSCSI drivers. You install Microsoft's iSCSI Initiator software on the client and then link the client and the R2000 (the iSCSI Target). The Getting Started wall poster is excellent and takes you through connecting to the management application and setting up iSCSI Initiators.

With iSCSI software in place, backups and restores are done to and from the client's virtual drive. That means you can transparently use any software that can do backups to disk, such as Veritas' Backup Exec. Since you're using a standard version of Backup Exec, you can even take advantage of the various agents Veritas provides to directly back up Microsoft Exchange and SQL, as well as Oracle and SAP databases. You can also use Backup Exec to perform replication and migration of files on the R2000 to iSCSI-attached tape drives.

The R2000 doesn't come with a tape/autoloader device, but the Overland Storage LoaderXpress with an LTO 2 tape drive and 11-cartridge autoloader is a good option.

Of note, as I was completing this review, Overland Storage released a replacement for the R2000 called the REO R4000, which supports iSCSI and/or higher bandwidth SCSI-FCP and up to 8 TB of internal disk. Disks are hot-swappable; you can set up as many as 16 virtual disk or tape LUNs to which clients can direct backups.

In addition, the R4000 supports LTO tape drive, but not autoloader emulation. It can back up Windows, Linux, Unix and NetWare clients, and is more than $10,000 cheaper than the R2000.

Barry Gerber (bg@bgerber.com) is a networking and storage consultant based in Los Angeles.