Spectra Stack.
Spectra Stack is the entry-class library in the Spectra Logic line: a stackable, modular system for institutions establishing a tape tier for the first time, or operating a working archive that does not yet warrant an enterprise frame. One specification separates it from the rest of its market tier — a 100% duty cycle, meaning it is rated for continuous operation rather than the intermittent duty entry-class libraries normally assume.
Entry class · Spectra EDGE Partner · Authorized reseller
Rated for continuous duty.
The duty-cycle rating is the specification that most often decides whether an entry-class library belongs in research computing at all. An archive tier operated against daily through HSM and migration workflows is not performing the intermittent duty an office-backup library is designed around. Most libraries at this price point are rated for partial duty; the Stack is rated for 24×7. Where a library will be under sustained load, that rating should be treated as a gating requirement rather than a line on a datasheet.
Growth is handled through a control module and up to six expansion modules, each in the same compact footprint. Capacity is licensed on demand in ten-slot increments from a ten-slot minimum, so the library can be bought at the scale the data currently requires rather than at the scale it is projected to reach. Expansion modules are added in under thirty minutes and without professional installation — which matters at sites that do not keep dedicated storage-hardware staff on payroll.
Media integrity is managed through the certified-media program and library-side monitoring used across the Spectra line, with an integrated Spectra Vision camera system for inventory and barcode verification. Encryption is available through BlueVision, and through KMIP for institutions already operating a central key-management service.
Capacity, module by module.
The figures below describe a fully expanded Stack — one control module and six expansion modules. Because capacity is licensed in ten-slot increments, most Stack deployments sit well below these numbers at installation and grow into them. Unique Checksum sizes the starting configuration against present data and the expansion schedule against observed growth rather than against the ceiling.
| Specification | Value |
|---|---|
| Maximum slots | 560 (control module plus six expansion modules) |
| Maximum native capacity | 22.4 PB (LTO-10) |
| Maximum compressed capacity | 56.0 PB (LTO-10, 2.5:1) |
| Maximum native throughput | 30.2 TB/hr (full-height drives) |
| Maximum compressed throughput | 90.7 TB/hr |
| Tape generations | LTO-5 through LTO-10 |
| Maximum drives | 42 half-height, or 21 full-height |
| Expansion model | Capacity on demand from 10 slots, in 10-slot increments |
| Module dimensions | 18.7 in W × 35.12 in D × 10.55 in H |
| Duty cycle | 100% — rated for continuous 24×7 operation |
| Reliability | MTBF 250,000 power-on hours; MTTR 3–10 minutes |
| Encryption | BlueVision; KMIP |
| Monitoring | Spectra Vision camera; media lifecycle management |
| Management | Color touch screen, or remote web interface |
Figures are Spectra Logic published specifications for the maximum configuration of this library family using current tape generations.
A first tape tier, sized honestly.
The Stack is specified where an institution is establishing a tape tier rather than expanding one: a first archive target, a departmental or project-scale preservation requirement, or a second site in a multi-site protection design.
Its ceiling is a scale many research-computing sites will eventually pass, and that is worth stating plainly at the point of purchase rather than discovering later. The mitigation is that nothing is stranded when it is passed — drives, certified media, and operational practice all carry forward into a Cube or a T950. An institution that expects to reach petabyte scale within the depreciation window should size against that expectation; one that does not should not pay for frames it will never fill.
The full library family is set out on the Spectra Logic page; the next tier is Spectra Cube.
Specifying an entry-class library.
Unique Checksum sizes entry-class deployments against the workload that will actually run, not against a capacity target. For a first tape tier that usually means a conversation about duty cycle, drive count, and the growth increment — the three decisions that determine whether the library is still appropriate in three years.
For a Spectra Stack conversation — configuration, capacity planning, media generation, or integration with an existing storage platform — write to sales@uniquechecksum.com.