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In modern data centers dominated by cloud native technology and NVMe SSDs, SCSI (Small Computer System Interface), an interface technology born in 1986, is still "alive" in tens of thousands of data centers worldwide. From government archives to medical imaging systems, SCSI cables provide unique compatibility to support enterprises in extracting residual value from outdated hardware while avoiding high migration risks.
SCSI protocol: the "living fossil" of data storage
SCSI was originally developed by Shugart Associates (predecessor of Seagate) to provide high-speed peripheral connectivity for early computers. Its parallel bus architecture supports daisy chain topology, and a single SCSI-2 cable can connect up to 16 devices (such as tape drives, hard disk arrays) in series. In the 1990s, the peak bandwidth of Ultra320 SCSI reached 320MB/s, which was once a standard configuration for high-end workstations.
Nowadays, although SAS (Serial Attached SCSI) and NVMe have taken over the mainstream market, according to IDC's 2023 report, about 12% of enterprise level storage devices worldwide still rely on traditional SCSI interfaces, mainly concentrated in the following scenarios:
Medical image archiving: Some MRI equipment from GE Healthcare still uses the SCSI-LVD interface to connect to storage servers. Due to upgrades, FDA compliance needs to be re certified, resulting in costs exceeding one million US dollars.
Legal Evidence Library: Several state courts in the United States require that criminal record storage media be retained for at least 30 years, resulting in a large number of SCSI tape libraries being unable to retire.
Industrial control system: The DCS (distributed control system) of the refinery adopts SCSI connection to the historical database, and the system renovation requires several months of shutdown.
Maintain the 'economic account' of old equipment
Why do companies prefer to maintain outdated SCSI devices rather than fully upgrade them? The answer lies in the game of cost and risk.
Case: The tape backup dilemma of a Japanese bank
A regional bank in Tokyo still uses IBM 3592 tape inventory with SCSI-3 interface to store customer transaction records. IT supervisor Kenichi Yamada calculated an account:
Upgrade cost: Replacing with LTO-9 tape library requires 300 million yen (approximately 2 million US dollars) and rewriting all backup scripts.
Maintenance cost: The existing system only requires an annual payment of 5 million yen (approximately 33000 US dollars) for replacing aging cables and cleaning magnetic heads.
As long as the SCSI devices are still operational, the board of directors will not approve the upgrade budget, "Yamada admitted.
This conservative strategy is not an isolated case. Gartner statistics show that in 2022, global enterprises will spend 5 billion on maintaining old IT systems, of which approximately 7% will be used for SCSI related hardware.
Compatibility challenges and the 'black market' ecosystem
The biggest pain point in maintaining SCSI infrastructure is supply chain disruption. Major manufacturers such as Adaptec have discontinued SCSI RAID cards, leading to a crazy premium in the second-hand market. The price of a brand new unopened Adaptec ASC-39320 (Ultra320 SCSI card) on eBay has skyrocketed from in 2019 to 00 in 2023.
Even more challenging is the issue of cable aging. The typical lifespan of SCSI-5 (Ultra5) cable is 10 years, and signal attenuation beyond this lifespan may result in catastrophic data damage. The Australian National Archives was unable to read census tapes from the 1980s due to an aging SCSI cable, and ultimately spent 0000 to rescue them through a professional data recovery company.
To address these challenges, companies adopt the following strategies:
Self made adapter: Convert the SCSI-68 pin interface to SAS and achieve cross generation compatibility through protocol conversion chips (such as PMC Sierra PM8003).
3D printing replacement: Dutch company RetroTech provides 3D printing services for SCSI terminal resistors at a price only 1/10 of the original parts.
Frozen spare parts warehouse: A European space agency stores SCSI controllers in a -20 ° C nitrogen gas cabinet to delay capacitor aging.
The dilemma of upgrading alternative solutions
For those enterprises that have finally decided to get rid of SCSI, the available paths are full of compromises:
Virtualization migration: Connect SCSI devices to a virtualization gateway (such as StarWind SCSI Target) and map them to SCSI LUNs for new system access. But the delay may increase by 20ms, which is not suitable for real-time systems.
Protocol simulation: Use tools such as QEMU to simulate SCSI controllers, but require recompiling old driver programs, with compatibility only around 70%.
Thorough replacement: The "SCSI retirement program" launched by the US Department of Defense in 2021 took 3 years, cost 0 million, and involved 12 million lines of code refactoring.
Will SCSI disappear in the future?
Although SCSI technology has been included in ISO/IEC's "list of obsolete technologies", its demise rate is much slower than expected. Technavio, a market research company, predicts that the market size of SCSI cables and related adapters will remain at 0 million by 2027, mainly from heavily regulated industries such as military and medical.
Technology nostalgia advocates have even initiated the 'SCSI revival movement'. At the 2023 DEF CON hacker conference, an engineer demonstrated using a Raspberry Pi to simulate a SCSI host controller and successfully read a 1989 Quantum ProDrive 50S hard drive. This is not just technology, but also digital archaeology, "emphasized the project initiator.
