Re: Looking for FOSS supported PCIe x4 SATA 6 Gb/s HBA with 4 or 8 ports
On 2020-02-10 13:55, Dan Purgert wrote:
On Feb 10, 2020, David Christensen wrote:
[...]
It has the following expansion slots:
- One PCI Express 2.0 x16 add-in card connector
- One PCI Express 2.0 x4 add-in card connector
- One PCI Express 2.0 x1 add-in card connector
a. While migrating backup data, I recently saw a Syba PCIe x1 two
port SATA II 3 Gb/s HBA model SD-SA2PEX-2IR throttling under
sustained load -- it ran at 80-100 MB/s for 4-5 minutes, then at
~7 MB/s for two hours. Unacceptable.
That controller makes no sense -- I think someone made a typo somewhere
on the specs (says it's a 2.5 Gb/sec PCIe x1 interface -- maybe they
meant it's PCIe 1.0 compliant, at 2.5 "gigatransfers" per second).
I assume you are referring to the Syba product page:
http://www.sybausa.com/index.php?route=product/product&product_id=172&search=SD-SA2PEX-2IR
Looking at Wikipedia, PCI Express link performance table:
https://en.wikipedia.org/wiki/PCI_Express#History_and_revisions
I believe 2.5 GT/s produces 2.5 Gb/s under PCIe version 1.0. So, the
Syba specification is correct in this case.
As I recall, PCIe 1.0 was in the neighborhood of 200MB/sec sustained for
a x1 slot;
Wikipedia indicates 250 MB/s throughput.
couple that with a slowish (or damaged) drive, or a
RAM-starved system, and a 7MB/sec transfer isn't exactly outside the
realm of possibilities. Granted, age of the card could also be a
factor.
When I connected the drive to a motherboard SATA port, the transfer
maintained 80-100 MB/s for the entire duration. That eliminates the
drive, the cable, and the RAM. I concluded the HBA was to blame. In
hindsight, it may have been a loose connection. It's not my computer,
so I will have to wait for an opportunity for further troubleshooting.
I am using another Syba SD-SA2PEX-2IR card in one of my computers with a
pair of Seagate ST31500341AS 1.5 TB drives. I used Seagate SeaTools
Bootable to erase both. The erase seemed to proceed okay. One drive
was visibly faster than the other. However, both jobs finished with
"100.00% FAIL". I am now using FreeBSD and hexdump to verify that the
drives are indeed full of zeros. iostat reports ~98 MB/s for one drive
and ~121 MB/s for the other.
When verification finishes in 4+ hours, maybe I'll do more
troubleshooting. Or, maybe I'll just proceed with the job I was
supposed to be doing right now but cannot because I bought the wrong
product.
That said, Seagate SeaTools is built with Tiny Core Linux. I previously
had a StarTech PEXSAT32 two port SATA III 6 Gb/s PCIe 2.0 x1 HBA in the
above computer. Tiny Core complained loudly during boot, and the drives
did not appear in the app. So, whatever StarTech did, Tiny Core did not
(or vice versa). I have put in a technical support request with both
StarTech and Seagate.
These are exactly the kinds of problems I want to avoid in a new HBA
purchase. I want to plug it in, connect a bunch of drives, and have
everything "just work".
David
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