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Port Multiplier / FIS Based Switching


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Im posting this incase anyone is considering going down the same road as me

I decided to buy a 4 Bay Esata Enclosure
Most around are Sata II

I found the Startech S3540BU33E £239.99 RRP
Sata III / USB 3.0 UASP
JMicron JMS567 USB 3.0 Bridge
JMicron JMB575 SATA III Port Muitiplier

In ESATA Mode the USB Bridge is bypassed so not a problem

I found what can only be described as the Startech's twin
DLSIM DLA614SUSJ3 its clearly made by the same company that
Startech are buying from and was only £79.99..

Now that it has arrived here's my view on it
which will also be valid for the startech version

All this is via ESATA no idea about USB Performance / Spindown ETC..

Hardware Bad Points

1) Led's far too bright
2) Power button needs to be a power switch
3) Clip on 70mm 3000 Rpm rear fan is noisy(HD7015S12L)(24.42CFM)
4) Drives slide home to sata port and flaps up if nudged

Hardware Good Points

1) Confirmed it comes with JMicron JMS567 + JMB575
2) Follows OS Spindown Plan (e.g. enclosure doesnt try spinning them down every few mins) (I Believe Startech Quote 5 or 10 min spindown with USB though)
3) If PC is powered off Enclosure detects this and powers hd's down and keeps them down until PC powers back on  
4)Enclosure is solid feeling should disipate heat ok

What i did to fix Bad Points

1) Covered led's with insulation tape to dim them (theyr behind front cover anyway)
2) Nothing
3) Removed Clip on 70mm fan and clip on Mechanism
plugs into pcb with same connector as xbox 360 controller rumble motors
Soldered spare connector to Dynamode 3 pin fan reduction cable + 1 extra Dynamode reduction cable
Mounted 80mm Coolermaster 2500rpm 22db Fan (- 900rpm for speed reducers so 1600rpm)
with 4 3mm x 80mm wide strips of 3M VHB, 4 other small pieces in corner contact points

This created a very good seal around the back far better than the old 70mm fan
it also covered the 70mm fan clip points

4) 3 layers of 3mm x 15mm 3M VHB on either side of the drive before sliding home (drives dont flap at all now)

Things you should be aware of about Port Multiplier / FIS Based Switching

1) Accessing a single drive gives full drive spec'd speed as expected
2) Having Sata II based drives in the mix seems to limit peak overall bandwidth to around 260 MB
3) Your drives are only as fast as the weakest link if saturating drives at the same time

Example 1
Drive 1 Capable of 205 MB/s Read
Drive 2 Capable of 125 MB/s Read
if you try reading them both at the same time (benchmark) you will get 125 MB/s from each drive

Example 2
Drive 1 Capable of 205 MB/s Read
Drive 2 Capable of 400+ MB/S Read (SSD)
if you try reading them both at the same time (benchmark) you will get 205 MB/s from each drive

If all drives are SATA III my Marvell 9230 seems capable of around 415-420 MB/s Per Port
If one of the drives are SATA II and all drives are saturating the link you only get 260 MB/s or so



Size Comparison




Drive Detection




Port Multiplier Chipset








Drive Flap Fix




Stock Rear 70mm Fan in clipon casing




80mm Fan Mod

(external cables was delib so i could add or remove fan reducers as needed)








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  • 1 month later...
  • 2 months later...

I have moved the rest of my 3tb drives (Sata III Drives) into the enclosure

in preparation for the 2 x 5TB Drives i have on order


anyway here's the effects of using port multipliers (fis based)


Green = One Drive being saturated

Red = Two Drives being saturated

Yellow = Three Drives being saturated

Blue = Four Drives being saturated


Remember the weakest link dictates the speed of all 4 drives

hence if you look at Red the start of the second drive is only capable of around 160 MB/S

then half way through the second drive moves to a faster part of the drive


Green = Drive Limited

Red = Drive Limited

Yellow = Sata Bus Limited

Blue = Sata Bus Limited



Edited by Shonk
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  • 3 weeks later...

Umm must find a card that takes 8 port multipliers


Im totally out of expansion room now


Internal Headers

1 x 240GB SSD

2 x 6TB WD

2 x 5TB Toshiba


Marvell 9230

3 x 2TB Samsung M9T Internal

1 x 3TB Toshiba ESATA Port Multiplier

3 x 3TB Seagate ESATA Port Multiplier



1 x 2TB Samsung M9T (Portable External)

1 x 500GB Hitachi (Portable External)

1 x 320GB Seagate (Portable External)

1 x 320GB Toshiba (Portable External)

1 x 320GB Samsung (Portable External)

1 x 320GB Samsung Internal


18 Drives..




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Thats a bit overkill for me


Im after a marvell 9230 2esata 2sata really with support for more than 7 drives


I know the chipset supports upto 20 drives

but i cant find one with support for more than 7 devices

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