Cheep mini sas controller.

[pawelb]

Hi, after read the article https://unraid-guides.com/2020/12/07/dont-ever-use-cheap-pci-e-sata-expansion-cards-with-unraid/

 

Im just courious, does it will work? Its cheap china controller

 

https://a.aliexpress.com/_mOUdcvu

 

For sure it's not raid so it should be hba, or should i look for one mentioned in an article? I need only 4 drives to work.

 

Thanks for help.

[Lolight]

5 hours ago, sunken-wren1932 said:

Hi, after read the article https://unraid-guides.com/2020/12/07/dont-ever-use-cheap-pci-e-sata-expansion-cards-with-unraid/

 

For sure it's not raid so it should be hba, or should i look for one mentioned in an article? I need only 4 drives to work.

Welcome!

 

That article expresses an opinion.

There are differing opinions on that point.

HBA's have downsides and should be avoided if possible., in my opinion.

 

How many HDDs in your system?

[pawelb]

hi, I've made my server only with 4 hdds and 1 or 2 ssd later. motherboard has only 2 sata ports. For now i've installed pcie 4x sata extension with ASMedia ASM1164, seams to be working, but found also opinion that its not ok for unraid.

[ConnerVT]

It looks as the card you bought is a PCIe x1 slot.  Not much info from your link (of course, AliExpress) but my guess is that it also has a multiplier chip, which is where the issue is.  It takes a single PCIe lane (data signal from your CPU) and splits it into 4 data signals to your drives.

 

In a desktop PC, where you are typically only accessing one drive at a time, this isn't a big issue.  But in Unraid, there are several cases when you are accessing multiple drives simultaneously.  Writing to the array (and one or two parity drives) or during a parity check (reading all array drives at the same time) is where this falls on it's face.  In both of these cases, the drives tend to fall into sync, where the drives all read/write in parallel with one another.  You will see this where the access speed starts off a bit slow, then increases up to (near) the drives maximum capable speeds.  With the controller needing to chop up the data one drive at a time, access speeds greatly suffer.

 

The blog you linked is somewhat correct: Marvel chips are well documented as to not play well with Unraid, and multipliers should definitely be avoided.  But using SAS HBA have their own issues:  Expense, cabling, heat and higher energy usage.  Best is to have a motherboard which has enough SATA ports to meet your needs (be aware some share PCIe lanes with NVMe slots, where some SATA connectors are disabled when a NVMe is installed).  If you need to add more SATA ports, a PCIe to SATA HBA is a viable option if you select correctly.  A PCIe x4 to 4 (or 5) SATA should be problem free.  I have a 5 port JMB585 in sy main server and it has been problem free.  ASM1164 (without a multiplier) is reported to work as well.

[JorgeB]

4 hours ago, pawelb said:

ASMedia ASM1164

This is fine for Unraid, at least the chip itself, some controllers may have better general quality than others, it's a 4 port controller without port multipliers, there are x1 and x2 versions (x4 physically), the latter one will have double the bandwidth.

[Lolight]

3 hours ago, ConnerVT said:

(be aware some share PCIe lanes with NVMe slots, where some SATA connectors are disabled when a NVMe is installed).

More often than not that's mostly applicable to the SATA, not NVMe type of M.2 devices, but yeah, it always pays to check mobo's storage specs at the manufacturer's site prior to purchasing.

[ConnerVT]

It really depends on the design of the motherboard, and how they deal out the available PCIe lanes to the motherboard resources.  I've seen some where it only affects things if the NVMe is SATA interface (vs PCIe), others where it is even more nuanced than that.

 

On one Gigabyte AB350M MB I have, it will disable 0, 1 or 2 SATA connections, depending on the M.2 NVMe interface.

 

On my MSI B-550-A Pro, adding a PCIe x4 NVMe (in the second M.2 slot) disables the motherboard's PCIe x4 slot.

 

As they say, YMMV.

Edited October 10, 2023 by ConnerVT