Expander, Speed

[MvL]

I want to use this case. https://www.xcase.co.uk/4u-rackmount-server-cases/x-case-rm-424-pro-with-sas-expander-sgpio-backplane-649-00-x-case.html It has a integrated expander in the backplane. How will this effect the speed of unRAID? I want to use 2 cables to connect to the backplane.

[JorgeB]

I believe you can only use one 4 port SAS cable for all 24 disks, for normal read/write operations it won’t make a difference, but this will considerably affect you parity check/syncs and disk rebuilds, by my calculations and with all 24 disks your max speed should be between 60 and 75MB/s.

[MvL]

Hi, thanks for answering!

 

Where do you base this on because if you check the video the guy explains that you can connect 2 sas cables to the backplane. So if I'm correct 12Gbit/s capacity a cable thus 24 Gbit/s in total. 24Gbit/s / 24 drives = 1 Gbit/s a drive. Is this correct? 

 

Edit: Hmm, yeah thus roughly 110MB/s a drive.., and st8000v2 drives can reach 200MB/s?

[JorgeB]

Is it this case?

 

 

 

[MvL]

I don't see anything...

 

This is the case X-CASE RM 424 PRO WITH SAS EXPANDER & SGPIO BACKPLANE. If you follow the link I posted in the first post you also see the case.

[JorgeB]

https://www.youtube.com/watch?v=BW7hpty1i9A

 

You should see the youtube video, copy/paste link, it has a single 4 port SAS connection

[MvL]

This is the video

https://youtu.be/SLz2muqcy98

 

Go to 3.40.

[JorgeB]

OK, looks like there are two models:

 

RM 424 Pro -with Expander – single 4 port SAS port

RM 424 Pro-EX Expander Version – dual SAS ports

 

The dual port version should be able to do ~110MB/s.

 

[MvL]

What is the speed when you connect the all drives to a HBA card?

[JorgeB]

In my tests, both SAS2LP and Dell H310 (flashed to LSI9211) with 8 SSDs max out at 320MB/s, so:

 

320 x 8 = 2560 / 24 = 106.66MB/s

[MvL]

Okay, clear! Thank you for your time.