SAS Expanders LSI or others

TrueNAS General
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1

The lore of TrueNAS says that if you want to add extra disk ports then use an LSI HBA, preferably 9200/9300 as others are “new” and less trusted.

So I have a 9300-8e and a spare slot in my server (the last spare slot - cry)

I could use a Dual Ports Mini SAS HD SFF-8644 to Internal SAS HD SFF-8643 PCBA Female Adapter | eBay and then directly cable some new disks in some sort of DIY disk shelf or I could use a SAS Expander as the direct cable solution may fall afoul of cable lengths

My question is can I use “any old” SAS Expander or am I limited to LSI. I cannot find an LSI SAS Expander with an external port but I can find an Adaptec SAS Expander which should do the job - but is it a good idea? Example of the type below

2

Why not using this? Any reason you want an expander?

3

Because (depending on where you are suggesting it goes:

  1. I have a 9300-8e for the main server - which is big enough. If I wanted more drives then your suggestion would be a good one.
  2. I want to avoid a motherboard / cpu / memory / OS for the expansion shelf. I just want Case, PSU and drives (plus associated cabling). I can use something like Mini PCIe to PCI 16X Riser PCI-E 16x Slot Adapter For Laptop External Card | eBay to power the expander - its just to supply power - no data required

I probably didn’t make clear that I am thinking that the “disk shelf” should be case, PSU, fans and wiring, no CPU, motherboard, memory etc

The reason for the expander (as opposed to the adapter) is that it solves the cable length issue for SATA disks

I have been unable to find any “cheap enough” units for sale in the UK

4

I use an Intel 36 port expander.

8 lanes ie ”ports” to it, leaves 28 ports for drives.

It works well, but they’re expensive now.

Most expanders should work well, but some do have issues, so you need to research the specific one you are looking at to ensure it doesn’t have known issues (I’m thinking of a specific cheap HP expander I believe, but am not sure )

many expanders use a PCIe slot for locating and power, but often this is not actually required, a give away is if there is a separate optional power input to the expander, say a peripheral molex
Connector.

5

Well the adaptec I linked to has 2 external ports and a molex along with more than enough internal ports so all I would need is a single (I might use 2) SFF-8644 to SF-8644 to connect the 9300 to the SAS Expander as well as the internal SSF-8643 to SAS/SATA Breakout cables

That el cheapo SAS adapter is only SAS2 (as printed on the PCB) - there is a much more expensive Startech one at £80+ that is probably SAS3 as there is a Supermicro one at a similar price - but using the adaptec would be a lot cheaper overall

So anyone else want to chime in and say “don’t use the adaptec because TrueNAS only uses LSI”?

6

The Adaptec expander follows the SAS3 spec. That’s all that any OS (TrueNAS included) cares about.

I also might add that the Adaptec is pretty much the go-to expander these days for home labs, as it can be found quite cheaply, and is very versatile.

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