Intel RES2CV240 and M1051 compatible

[Doug183]

I want to drive 40 drives with FreeNAS in one big case.

1) Will a flashed M1051 card drive an Intel RES2CV240 expander in FreeNAS trouble free?
2) Will ONE flashed M1051 card drive TWO Intel RES2CV240 expanders, so I can have 40 drives available in FreeNAS?

Please, don't hijack the thread and ask why I need so much room for my porn - which I do but this is not what I am using this server for or suggest other solutions (which I want but distracts people from answering this question.)

Please also I am looking for people who have implemented this solution or can post a link to a reports that this works or not. Basically I know it SHOULD work, but I want to hear from people who actually use this setup and can tell me what works and what doesn't work. (and yes, I have googled this and I haven't seen someone post this their hardware and it succeeded/failed with FreeNAS.)

I hear cyberjock likes this hardware, but can't find any posting to confirm.

Thanks
Doug

 

[Doug183]

Ok, answered my own question, at least found out that one M1015 will drive one Intel RES2CV240. Its on cyberjock's hardware page. He does't list the part number which is why it doesn't come up in my search. Its listed in the bottom of this thread.

https://forums.freenas.org/index.php?threads/hardware-recommendations-read-this-first.23069/

 

[Doug183]

Ok, but can I run two Intel Expanders off an M1015 to get to 40 drives?

 

[Darren Myers]

I think that would hamper the SATA speeds attaching 40 odd drives to a single controller, granted yes SAS will do 128 or something devices i think (something like that) i would much rather have 2 M1015's 1 for each expander. This is from @jgreco 's SAS'y thread

SAS Expanders

A SAS expander essentially takes a SAS multilane connection and allows the attachment of additional SAS devices. These devices all share in the available bandwidth of the SAS multilane connection. SAS expanders can be cascaded as well. In the following picture:

we see three SAS expanders. The first one only distributes to the second and third. The second and third each attach to hard disks. Modern expanders typically have enough channels that you wouldn't need to cascade them for just this small number of disks. A typical modern expander might have 36 lanes, allowing 24 disks, two upstream four lane host connections, and a downstream four lane connection to another expander.

There are advantages and disadvantages to expanders. A primary advantage is cabling simplicity: if you have a 24 drive chassis with a backplane that uses an expander, you need only a single SFF8087 to attach from the backplane to the HBA. The two main downsides are that those 24 drives then share the 24Gbps that's available on a SFF8087, and that in some cases some specific SATA disks have been known to not play nicely and have caused problems for other attached devices on a SAS expander.

As a matter of throughput, a typical modern hard drive can push 125-150MBytes/sec (that's about 1-1.25Gbps) so if you load up 24 disks * 1.25Gbps, you do exceed the 24Gbps that the multilane is capable of. This, however, assumes that you are doing sequential access to all drives simultaneously. That is unlikely at best.

The picture changes for SSD, and expanders may not be a good idea for use with large numbers of SSD's if you are expecting high throughput.

 

[Ericloewe]

Ok, but can I run two Intel Expanders off an M1015 to get to 40 drives?

Yes.

 

[jbates58]

hello doug.

i tried to send you a PM, but im not sure if i did it correctly. i started a conversation with you so im hoping that they are the same thing.

Jason

 

[SirMaster]

I think that would hamper the SATA speeds attaching 40 odd drives to a single controller, granted yes SAS will do 128 or something devices i think (something like that) i would much rather have 2 M1015's 1 for each expander. This is from @jgreco 's SAS'y thread

With 40 disks on a single M1015 you are going to be able to get 4000MB/s from the 8x PCIe 2.0 bus which will be 100MB/s per disk if they are all going at once. Which in practice shouldn't really be noticeably limiting anything.