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Home > Products > Host Controllers > Port Multiplier Tutorial

last update: August 10, 2011 Printable Version

What are Port Multipliers (PM)?

Port Multipliers allow the connection of multiple Serial ATA devices to systems through a single Serial ATA port. Port Multipliers can be used for connecting any Serial ATA device, including SATA hard drives, SSD (solid state drive), other types of flash memory with SATA interface or SATA optical drives. The Port Multiplier offers unprecedented scalability, breaking the traditional Serial ATA connection topology of a single SATA device per port.

All the key advantages of Serial ATA technology over comparable interface solutions are preserved in the Port Multiplier. Both Serial ATA 1.5Gbps and Serial ATA 3.0Gbps devices are compatible, and the PM retains the 3.0Gbps SATA channel for connection to the SATA controller installed inside the host machine. With a supported 3.0Gbps SATA device and SATA controller, the Port Multiplier is able to take advantage of NCQ (Native Command Queuing). Similar to it's lower speed competitors USB 2.0/1.1 and Firewire 400/800, devices connecting to the PM hot swapped without system reset.

What are the benefits of using a Port Multiplier?

  1. Port Multipliers increase the number of SATA devices which can be connected onto a single controller.

    Prior to the Port Multiplier, SATA controllers with 4 Serial ATA ports are limited to 4 SATA devices, one per port. To increase the amount of drives on the system, additional SATA controllers must be installed. With a Port Multiplier supporting up to 5 hard drives attached onto each of the SATA ports, a controller previously limited to 4 SATA devices is now able to simultaneously connect up to 20 SATA devices. This is beneficial to users who own a motherboard with very few or no bus slots available for adding SATA controllers.

    Example of a system configuration
    without Port Multipliers
    Example of a system configuration
    with Port Multipliers

  2. Port Multipliers reduce the amount of cabling required to connect an array of SATA devices.

    The SATA Port Multiplier combines several SATA devices into a single high speed 3.0Gbps SATA connection. In particular, this is an improvement for eSATA external storage units by allowing the convenience of only needing to connect one eSATA cable instead of requiring one cable per each device, with no substantial decrease in data transfer speed.

  3. Port Multipliers are available with built-in Hardware RAID controllers for combining drives.

    Hardware RAID Port Multipliers are a great option when considering the creation of a redundant data storage solution. RAID capability is attributed to the built-in RISC chips which assume the load of handling RAID parity calculations, resulting in superior performance over software RAID sets which direct the processing load to the system CPU. At the same time, implementation of Hardware Port Multipliers avoid the cost of expensive Hardware RAID SATA controllers. The Silicon Image 4726 chip is able to create RAID 0, 1, JBOD, SAFE FAST, and SAFE BIG. The Oxford OXUFS936QSE chip is able to create FAST2 (2 drive RAID0 Striping), FAST4 (4 drive RAID0 Striping), SAFE2 (RAID1 Mirroring), SAFE FAST (Mirrored Striped), BIG 2 (2 drive Concatenation), BIG 4(4 drive Concatenation), RAID 3+S, or RAID 5+S using built-in hardware RAID.

  4. A potentially unlimited number of hard drives can be daisy chained to a single SATA port using Hardware Port Multipliers.

    With a Hardware RAID Port Multiplier, drives connected configured as a single RAID volume (for example, a blazing fast 5 drive Striped set) can be attached onto any SATA port whether or not it is port multiplier compatible. This allows for a potentially unlimited amount of storage capacity by daisy chaining up to 5 Hardware Port Multipliers each fully populated with 5 hard drives onto one Hardware Port Multiplier for a total capacity of 25 hard drives through a single SATA or eSATA port. To the operating system all the drives appear as a single volume, yet a redundant RAID set still retains the ability to rebuild the RAID under the situation of data loss.




  5. Port Multipliers are not only limited to SATA or eSATA interface.

    Newer Port Multipliers or storage enclosures utilizing Port Multiplier ASIC may now include other common interfaces such as USB 2.0, Firewire 400, or Firewire 800. For systems which do not have an available SATA or eSATA port to attach a Port Multiplier, these alternative interfaces can be used instead for better compatibility. eSATA to USB 2.0 Adapters (AAU3ESA) can be attached onto Port Multipliers based on the 3726 which have no built-in USB support, allowing the connected drives to be seen as separate devices or as a single RAID volume on any computer with a USB 2.0/1.1 port. With hard drives set up as a single RAID volume using a hardware RAID port multiplier, the RAID volume can be connected to the computer through USB 3.0 using the Addonics USB 3.0 to eSATAp Adapter.


Port Multiplier chipsets

  1. Silicon Image 3726
  2. Silicon Image 4726
  3. Silicon Image 5744
  4. Oxford OXUFS936QSE
  5. JMicron JMB393



Addonics Port Multiplier Comparison Chart 1 (see chart 2 below for additional models)
Model #
AD5HPMREU AD5HPMSXA AD5HPMRXA-E AD4SR5HPMU-E AD4SR5HPMUS

         
Type of Port Multiplier
Hardware Port Multiplier (HPM)
Hardware Port Multiplier (HPM)
Hardware Port Multiplier (HPM) Hardware Port Multiplier (HPM) Hardware Port Multiplier (HPM)
Maximum number of storage Devices supported
5 5 5 4 4
Connect to system via SATA port
Yes. Any SATA port
Yes. Any SATA port
Yes. Any eSATA port
Yes. Any eSATA port
Yes, Any SATA port
Connect to system via USB port
Yes, support USB 3.0 and USB 2.0 requires optional Addonics USB 3.0 - eSATA adapter (AAU3ESA) requires optional Addonics USB 3.0 - eSATA adapter (AAU3ESA) Yes, USB 2.0 Yes, USB 2.0
Supported enclosures or systems
  • Rack mounted system with SCSI-I cut out.
  • Addonics Storage
      Tower, Mini Storage
      Tower or Storage Rack
    .
  • SCSI enclosure with SCSI-I back panel

Standard computer case with 1 free standard height or low profile PCI slot

  • Rack mounted system with SCSI-I cut out.
  • Addonics Storage
      Tower, Mini Storage
      Tower or Storage Rack
    .
  • SCSI enclosure with SCSI-I back panel
  • Rack mounted system with SCSI-I cut out.
  • Addonics Storage
      Tower, Mini Storage
      Tower or Storage Rack
    .
  • SCSI enclosure with SCSI-I back panel .
Standard computer case with 1 free standard height or low profile PCI slot
RAID Configuration requirement
using a set of onboard dip switches or RAID utility software using a set of onboard dip switches or RAID utility software using a set of onboard dip switches or RAID utility software
using onboard rotary switch
using onboard rotary switch
Supported RAID functions
RAID 0, 1, 10, BigDrive, 5, 5+S. RAID 0, 1, 10, BigDrive, 5, 5+S. RAID 0, 1, 10, BigDrive, 5, 5+S. FAST2 (2 drive RAID0), FAST4 (4 drive RAID0 S), SAFE2 (RAID1), SAFE FAST (RAID 10), BIG 2 (2 drive Concatenation), BIG 4(4 drive Concatenation), RAID 5, or RAID 5+S FAST2 (2 drive RAID0), FAST4 (4 drive RAID0 S), SAFE2 (RAID1), SAFE FAST (RAID 10), BIG 2 (2 drive Concatenation), BIG 4(4 drive Concatenation), RAID 5, or RAID 5+S
Drives can be configured to appear as individual drive to the OS
Yes when connecting to PM compatible controller or USB port Yes when connecting to PM compatible controller or USB port Yes when connecting to PM compatible controller or USB port No No
Integrated RAID controller
Yes Yes Yes Yes Yes
Bootable
Yes Yes Yes Yes Yes
Supported Type of Storage Devices
SATA hard drives, SATA SSD, CF (with Addonics SATA-CF adapters) SATA hard drives, SSD, optical driveCF (with Addonics SATA-CF adapters) SATA hard drives, SATA SSD, optical drive, CF (with Addonics SATA-CF adapters) SATA hard drives, SATA SSD, CF (with Addonics SATA-CF adapters) SATA hard drives, SATA SSD, CF (with Addonics SATA-CF adapters)
Host Link Speed
1.5 / 3Gbits/s 1.5 / 3Gbits/s 1.5 / 3Gbits/s 1.5 / 3Gbits/s 1.5 / 3Gbits/s
SATA optical drive support
Yes when connecting to PM compatible SATA controller Yes when connecting to PM compatible SATA controller Yes when connecting to PM compatible SATA controller No No
RAID status diagnostic
PM monitoring software PM monitoring software PM monitoring software
via a lighting sequence of LEDs (LEDs are not included, pin header for LED is provided onboard)
via a lighting sequence of LEDs (LEDs are not included, pin header for LED is provided onboard)
Support email notification
Yes Yes Yes No No
Maximum storage volume capacity
2TB with a 32-bit OS, 256TB theoretical maximum with 64-bit OS 2TB with a 32-bit OS, 256TB theoretical maximum with 64-bit OS 2TB with a 32-bit OS, 256TB theoretical maximum with 64-bit OS 2TB with a 32-bit OS, 256TB theoretical maximum with 64-bit OS 2TB with a 32-bit OS, 256TB theoretical maximum with 64-bit OS
LED connectors
Host link, storage device, individual drive activity, power and system ready Host link, storage device, individual drive activity, power and system ready Host link, storage device, individual drive activity, power and system ready Host link, RAID status, individual drive activity, power, system ready and RAID diagnostic Host link, RAID status, individual drive activity, power, system ready and RAID diagnostic
Supported Operating Systems
OS independent OS independent OS independent OS independent OS independent
Storage device can be hot swapped from the Port Multiplier
Yes Yes Yes Yes Yes
Port Multiplier can be hot swap from host
Depends on controller Depends on controller Depends on controller Depends on controller Depends on controller
Daisy chain multiple Port Multipliers
Yes Yes Yes Yes Yes
Dimensions (W x D x H)
85 mm x 55 mm x 23 mm 85mm x 55mm x 23mm 85 mm x 55 mm x 23 mm 85mm x 55mm x 23mm 85mm x 55mm x 23mm
power connection requirement
standard floppy power connector standard floppy power connector standard floppy power connector standard floppy power connector standard floppy power connector
Chipset
JMB393 JMB393 JMB393 OXUFS936QSE OXUFS936QSE

 

Addonics Port Multiplier Comparison Chart 2
Model # AD5SARPM-E AD5SAPM AD5SAHPM-EA AD5ESAPM-E
 
         
Type of Port Multiplier Port Multiplier Port Multiplier Hardware Port Multiplier (HPM) Port Multiplier
Maximum number of Storage Devices supported 5 5 5 5
Connect to system via SATA port
Yes. PM-compatible eSATA port
Yes. PM-compatible SATA port
Yes. Any eSATA port
Yes. PM-compatible eSATA port
Connect to system via USB port requires optional Addonics USB 3.0 - eSATA adapter (AAU3ESA). No RAID support requires optional Addonics USB 3.0 - eSATA adapter (AAU3ESA). No RAID support requires optional Addonics USB 3.0 - eSATA adapter (AAU3ESA) requires optional Addonics USB 3.0 - eSATA adapter (AAU3ESA). No RAID support
Supported enclosures or systems
  • Rack mounted system with SCSI-I cut out.
  • Addonics Storage
      Tower, Mini Storage
      Tower or Storage Rack
    .
  • SCSI enclosure with SCSI-I back panel .
Standard computer case with 1 free PCI slot
  • Rack mounted system with SCSI-I cut out.
  • Addonics Storage
      Tower, Mini Storage
      Tower or Storage Rack
    .
  • SCSI enclosure with SCSI-I back panel .
External
RAID Configuration requirement
using the RAID utility1 of the SATA controller
using the RAID utility1 of the SATA controller
Connect to PM compatible controller or USB 2.0 port and use PM software utility
using the RAID utility1 of the SATA controller
Supported RAID functions
Dependent on the controller
Dependent on the controller
RAID 0, 1, 10, BigDrive.
Dependent on the controller
Drives can be configured to appear as individual drive to the OS Yes when connecting to PM compatible controller or USB 2.0 port Yes when connecting to PM compatible controller or USB 2.0 port Yes when connecting to PM compatible controller or USB 2.0 port Yes when connecting to PM compatible controller or USB 2.0 port
Integrated RAID controller No No Yes No
Bootable No No Yes No
Supported Type of Storage Devices ATA hard drives, SATA SSD, CF (with Addonics SATA-CF adapters) SATA hard drives, SATA SSD, CF (with Addonics SATA-CF adapters) ATA hard drives, SATA SSD, CF (with Addonics SATA-CF adapters) eSATA hard drives, eSATA SSD
Host Link Speed 1.5 / 3Gbits/s 1.5 / 3Gbits/s 1.5 / 3Gbits/s 1.5 / 3Gbits/s
SATA optical drive support Yes (cannot be used in simultaneous burn application) Yes (cannot be used in simultaneous burn application) Yes when connecting to PM compatible SATA controller (cannot be used in simultaneous burn application) Yes (cannot be used in simultaneous burn application)
RAID status diagnostic PM monitoring software PM monitoring software PM monitoring software PM monitoring software
Support email notification No No No No
Maximum storage volume capacity 2TB with a 32-bit OS, 256TB theoretical maximum with 64-bit OS 2TB with a 32-bit OS, 256TB theoretical maximum with 64-bit OS 2TB with a 32-bit OS, 256TB theoretical maximum with 64-bit OS 2TB with a 32-bit OS, 256TB theoretical maximum with 64-bit OS
LED connectors Host link, storage device, individual drive activity, power and system ready Host link, storage device, individual drive activity, power and system ready Host link, storage device, individual drive activity, power and system ready Host link, storage device, individual drive activity, power and system ready
Supported Operating Systems Windows 2000, XP, 2003, Vista, Mac OS X and above, Linux kernel 2.62 and above Windows 2000, XP, 2003, Vista, Mac OS X and above, Linux kernel 2.62 and above OS independent Windows 2000, XP, 2003, Vista, Mac OS X and above, Linux kernel 2.62 and above
Storage device can be hot swapped from the Port Multiplier Yes Yes Yes Yes
Port Multiplier can be hot swap from host Depends on controller Depends on controller Depends on controller Depends on controller
Daisy chain multiple Port Multipliers No No Yes No
Dimensions (W x D x H) 85 mm x 55 mm x 23 mm 85 mm x 22 mm x 49 mm 85mm x 55mm x 23mm 135mm x 65mm x 25mm
power connection requirement standard floppy power connector standard floppy power connector standard floppy power connector External 5V power adapter
Chipset SiI3726 SiI3726 SiI4726 SiI3726

note:

1 Setting of the Port Multiplier requires configuration software from the controller, with the exception of the Hardware Port Multiplier (which uses it's own configuration software). All Addonics controllers only include the software to configure the standard Port Multiplier under Windows OS at this time.
2 Certain Linux distributions must patch the kernel with libata-tj-stable before they will support the Port Multiplier. Click here for instructions on how to patch the kernel under several Linux distributions.