History 2004: Disk and Tape Together on ADIC’s Pathlight

The new version 2.0 of ADIC’s Pathlight VX, available next January, is apparently the first mid-range backup subsystem integrating disk and tape drives in a single and unified environment.

Not to be confused with IBM’s virtual tape libraries or those by StorageTek, with disk and tape already integrated, as well as HDDs, which function only as frontal cache for the tape drives.

There are also some low-end D2D2T, such as those supplied by Certance or Synerway.

The new Pathlight is thus truly a D2D2T integrated solution. The disk array portion ranges from 3.8 to 46.8TB on SATA drives. Here, it’s a Clariion from EMC, with which ADIC recently signed a joint agreement, whereby the latter resells its tape libraries, and the 2nd integrates within the Clariion unit.

The tape portion goes as high as native 2.8PB (with the Scalar 10K) in LTO-2, which can be divided in 32 virtual libraries, based on an ADIC Scalar model or a StorageTek L180 and L?00 library.

The total unit is fairly impressive, where the disk portion consists of 12×19-inch rack units at nearly 50kg, not to mention the tape side.

Practically speaking, behind the 1/0 controller that drives the whole, and on which we find the actual ADIC hardware and software contribution, is an FC switch placed on the front of the Clariion and the tape library. The advantage of backup, in this case on disks, is clearly the backup and restore speed. ADIC estimates that performance doubles compared to tapes, reaching some 54-56MB/s for large files and 18-23MB/s for small files, on backup as well as restore, without concern for tape positioning or “shoe shining.”

Instead of reflecting the number of physical tape drives effectively present within the library, Pathlight indicates the backup software with up to 40 virtual units, which allows it thus to run 40 simultaneous backup operations, each one at full speed.

For the system, the Pathlight looks like a conventional 2Gb/s FC tape library, and thus doesn’t require a license for more than 1 robotic system.

It can be managed by traditional backup software from Veritas or Legato for example, although the data must initially be written on faster disks. They then move to tape, depending on policy set by the user, but are accessed transparently by the application through a single point of access.

For archiving or disaster recovery, tape cartridges, written offline via the internal fabric in the native format of the backup software, can be duplicated on up to 4 copies, and exported and stored in a safe place.

ADIC’s StorNext software provides, in the background, the data management options between disk and tapes, policy-based data movement and optimization of streaming performance.

For example, the user can choose to store 1 week or 1 month of data on disk, depending on the capacity selected, subsequently transferred automatically to tape. This leaves the user the difficult task of setting the proper division of capacity between faster and even more expensive direct access media, vs. the lower-cost but slow sequential access media.

Pathlight’s pricing depends heavily on the selection of capacities in both disk and tape. The company indicates a cost of roughly $15.8/GB for 45TB on disk only, compared to only $7.5/GB in the event an equal balance between capacity and the 2 media is required, including 3 to 4 tape drives.

This article is an abstract of news published on issue 203 on December 2004 from the former paper version of Computer Data  Storage Newsletter.