Why use a SCSI Switch?SCSI switch overview

  • Share SCSI Devices between Multiple Hosts to maximise the peripheral investment.
  • Can be used to provide failover or failsafe protection when sharing SCSI RAID or Tape Libraries between an active host and a dormant host.
  • As a low cost alternative to a SAN
  • Use A SCSI Switch to extend the SCSI bus length beyond the 20 M limit
  • Complete hardware only solution- no software required.


  • Choose the number of Host SCSI channels (2 x 1, 3 x 1, 4 x 1 etc.)
  • Choose the number of Target SCSI channels.  If more than 1 (i.e. 2 x 2 ) then this is a Matrix Switch where any Host Channel can be connected to any Target Channel
  • Choose the SCSI bus type.  (LVD, HVD or SE SCSI) or a mixture of these buses in the Switch
  • Choose the method of controlling the Switch. (Dynamic Switching, Manual control, control over the Network as a Network device, or Automatic Control via the SCSI bus itself or via a serial bus)

Switch Specifications

  • 160 Mbytes/sec Bandwidth
  • SCSI buses are totally isolated from each other, re-timed and regenerated, so that they can run the full length in either direction.
  • Each Bus segment is individually terminated. LVD buses have multi-mode termination
  • Bus Switching maintains correct termination, and only occurs at SCSI bus free
  • Suitable for HVD, LVD or SE SCSI, or a mixture of these
  • Rackmount or Desktop versions available

Available Switches

Dynamic SCSI Switch

DynamicDesigned for the IBM AS400/iSeries with HVD SCSI interfaces, the Dynamic SCSI Switch offers a simple way to maximize the investment in high value tape drives or libraries by sharing them between systems. A Dynamic SCSI Switch makes this possible and will also save money on maintenance and manpower, enabling backup and restore operations onto different hosts, and across platforms. This is all achieved without the need for physical switching or special software.

Supported Drives:
IBM 3570, 3590, 3490, LTO Ultrium 3580, 3581 Autoloader, Fujitsu 3590, DLT, AIT and 8mm and most Libraries.

Download the Dynamic SCSI switch data sheet in pdf format

Manual SCSI Switch

ManualCompatible with all modern tape drives, including the complete LTO range.  LTO (Linear Tape Open) is setting new standards in high performance tape technology. Available from IBM, HP, and Quantum with compatible media. Standard single host attachment, a simple SCSI Switch will connect a second host to a shared device.

Switch Features

  • Simple dependable way to maximize the value of your SCSI tape investment.
  • Hardware only solution – no special software or patches needed.
  • Simple plug and play installation.
  • Zero overhead: up to 160 Mbyte per second bandwidth – no speed loss.
  • Continuous availability to both hosts – benign message informs one host if drive is already in use.
  • Save on Hardware and Future Tape Maintenance costs.
  • Host fail-over protection for SCSI Raid and tape libraries.
  • Available as a 3rd and / or 4th host attachment for IBM 3590 drives.
  • All Avax SCSI switch solutions are 100% compatible with IBM iSeries (AS/400) , RS/6000, Microsoft, HP, Sun, DEC Alpha and most other computer systems.

Download the Manual LVD SCSI switch data sheet in pdf format

NOTE: We still offer switches for legacy Single Ended (SE) SCSI devices.

Web Controlled SCSI Switch

  • SWebControlledhare SCSI Devices between Multiple Hosts to maximize the peripheral investment
  • Controlled automatically via the intranet—The Switch acts as a Web Server, and its configuration can be controlled using standard Windows (or Unix) task scheduler
  • Can be used to provide failover or failsafe protection when sharing SCSI RAID or Tape Libraries between an active host and a dormant host
  • A low cost alternative to a SAN
  • Matrix Switches 2 x 2, 3 x 2 and 4 x 2 available.

Download the Web Controlled SCSI switch data sheet in pdf format

Server Clustering Switch (High Availability)

ServerClusterHigh availability computer systems require Shared Disks and Tape/Libraries, but sharing by joining the SCSI buses between servers can be problematic. Consideration must be given to shared termination and bus stub lengths but the Avax Server Clustering Solution overcomes all of these problems. By allowing bus segments to be created that are totally regenerated and re-timed, these are isolated from the adjoining buses. This also allows the disks to be placed up to 25 metres from the hosts.

  • Share a Disk or Tape between 2 or more Hosts
  • Sharing can be manual or dynamic / automatic
  • Hardware only solution – no special software or patches
  • Available for HVD or LVD hosts, or a combination
  • PCB provides complete SCSI isolation between hosts. Each host has an independently terminated bus that is not affected by the bus switching
  • Simple and dependable

Download the Server Clustering Switch datasheet: click here. (pdf)

Multi-Ported Tape Drive

MultiPortedIf the tape drive is in use by one host, and another host attempts access, it will receive a “device reserved” response until the original host has completed it’s task. To each of the hosts it looks like a tape drive is attached and backups/restores will run at the maximum drive transfer rate.
Each server will have a copy of backup software running. The Multi-Serve will be able to backup from any other servers connected over the network. When scheduled backups start the tape drive will read the tape in the drive and append data to the tape. This system also allows restores to be performed at full tape drive transfer rates, with no network traffic overheads.


Partition a Tape or CD library and its slots into two or more independent virtual libraries each with its own isolated SCSI input.

It is often desirable to share a Large Library between a number of hosts. The traditional Client-Server approach to this problem has a number of disadvantages, which are overcome by the virtual library approach.

  • The backup data rate is degraded by the network – it is better to backup from each host via a direct SCSI connection
  • Splitting the library allows the use of lower cost Single Server Management software.
  • Eliminates the need for slot pooling and allocation between hosts.
  • Allows hosts of different types, with different software to share a single library

Custom Switches

In addition to our standard range, Avax can design and build custom SCSI switches to your specifications.  Mixed bus types, matrix and  multi way switches are all possible.

Contact your Avax sales representative for more details.