Archive for April, 2023

Switch-Based NVMe Hotplug – a Few Attempts, and one Success

Monday, April 10th, 2023

Let’s say you’ve just bought a chassis with an NVMe backplane, or retrofit one into your chassis. Now, it’s time to see if we can get hotplugging and backplane management working.

First of all, PCIe hotplugging is hard. It’s nothing new – after all, PCI hotplug has been around in the form of PCMCIA cards for decades, and PCIe got the same treatment with the later ExpressCard standard. But the reality is that whether it’s a laptop with a card slot, a system with Thunderbolt, or a server with an NVMe backplane, it’s one of those things that you can only expect to work seamlessly if you buy a full OEM system validated for that purpose. If you cobble together a machine from parts, it’s much more difficult to get any sort of PCIe hotplugging working.

I went through this recently after adding a U.2 backplane. Here’s a few things I tried, some of which worked better than others.


Upgrading an SC847 with a rear 2×2.5″ Drive Cage

Saturday, April 8th, 2023

I read this post about upgrading an older SC826 to support the rear drive cage option, and wondered if I could do the same with an SC847. The newer ‘B’ models support this natively, but there are still tons of cheap non-B models out there.

The first question is “why”? To which there are several answers:

  • More drives! Free up a couple 3.5″ bays for 3.5″ drives, rather than using an entire 3.5″ bay for a 2.5″ drive.
  • Cheapest NVMe option. $60-65 for the upgraded motherboard tray, and $80-90 for the drive cage, compared to $200 or so for the 4x U.2 rear backplane.
  • More NVMe. You could get both the 4x U.2 rear backplane (BPN-SAS3-826EL1-N4) and the rear 2x NVMe cage for 6 NVMe bays. (There is also an 8x U.2 front backplane, but it’s hard to find). for a little over $200. The 8x U.2 front backplane is much more difficult to find. Maybe 4 NVMe bays isn’t quite enough for you.
  • Dual-expander (EL2) backplanes: There are no backplane options with both dual SAS expanders and NVMe support.

Enough intro, I was able to get this conversion working, and it was much easier than the 826 conversion (though took a lot longer). Here’s how.


Restoring eBay’s Sale History Link

Friday, April 7th, 2023

It’s very useful to be able to see the sale history for an item that isn’t yours. You might want to see how quickly it sells, or whether offers are likely to be accepted or rejected. Unfortunately, eBay seems to have recently removed this link. The good news is that the page still exists and can be accessed via the same URL as before. Here’s a GreaseMonkey script to turn the “x sold” text into a clickable link like it previously was:

// ==UserScript== 
// @name     Restore eBay sold items link 
// @version  1
// @grant    none
// @match *://**
// ==/UserScript==

element = document.querySelector("div.d-quantity__availability span:last-child")
text = element.textContent
re = /(.*)\/itm\/([0-9]+).*/
url = document.location.href.replace(re, '$1/bin/purchaseHistory?item=$2')
element.innerHTML = '<a href="' + url + '">' + text + '</a>'

I have not tested it on other userscript plugins. The end result looks like this:

Clicking the link takes you to the sale history page:

Broadcom 9400 – Should You Buy One for a Homelab?

Monday, April 3rd, 2023

The 9400 series is LSI/Avago/Broadcom’s first “Tri-Mode” HBA, capable of supporting SAS, SATA, and NVMe all in one adapter. There’s a few catches, but despite that, it might still be worth the buy depending on your circumstances.