Comment on Am I corrupting my data?
Nollij@sopuli.xyz 2 days agoI don’t want to speak to your specific use case, as it’s outside of my wheelhouse. My main point was that SATA cards are a problem.
As for LSi SAS cards, there’s a lot of details that probably don’t (but could) matter to you. PCIe generation, connectors, lanes, etc. There are threads on various other homelab forums, truenas, unraid, etc. Some models (like the 9212-4i4e, meaning it has 4 internal and 4 external lanes) have native SATA ports that are convenient, but most will have a SAS connector or two. You’d need a matching (forward) breakout cable to connect to SATA. Note that there are several common connectors, with internal and external versions of each.
You can use the external connectors (e.g. SFF-8088) as long as you have a matching (e.g. SFF-8088 SAS-SATA) breakout cable, and are willing to route the cable accordingly. Internal connectors are simpler, but might be in lower supply.
If you just need a simple controller card to handle a few drives without major speed concerns, and it will not be the boot drive, here are the things you need to watch for:
- MUST be LSi, but it can be rebranded LSi. This includes certain cards from Dell and IBM, but not all.
- Must support Initiator Target (IT) mode. The alternative is Initiator RAID (IR) mode. This is nearly all, since most can be flashed to IT mode regardless
- Watch for counterfeits! There are a bunch of these out there. My best advice is to find IT recyclers on eBay. These cards are a dime a dozen in old, decommissioned servers. They’re eager to sell them to whomever wants them.
Also, make sure you can point a fan at it. They’re designed for rackmount server chassis, so desktop-style cases don’t usually have the airflow needed.
thelemonalex@lemmy.world 1 day ago
Thank you very much for the detailed information. I’ll look into eBay again, maybe I can find a good offer that works. I’m unsure how to choose the number of lanes. Does that relate to the number of drives it supports? Also, in terms of cooling, would any PC case fan be enough, if strapped onto the HBA?
Nollij@sopuli.xyz 1 day ago
Kind of. They will be multiples of 4. Let’s say you got a gigantic 8i8e card, albeit unlikely. That would (probably) have 2 internal and 2 external SAS connectors. Your standard breakout cables will split each one into 4 SATA cables (up to 16 SATA ports if you used all 4 SAS ports and breakout cables), each running at full (SAS) speed.
But what if you were running an enterprise file server with a hundred drives, as many of these once were? You can’t cram dozens of these cards into a server, there aren’t enough PCIe slots/lanes. Well, there are SAS expansion cards, which basically act as a splitter. They will share those 4 lanes, potentially creating a bottleneck. But this is where SAS and SATA speeds differ- these are SAS lanes, which are (probably) double what SATA can do. So with expanders, you could attach 8 SATA drives to every 4 SAS lanes and still run at full speed. And if you need capacity more than speed, expanders allow you to split those 4 lanes to 24 drives. These are typically built into the drive backplane/DAS.
thelemonalex@lemmy.world 16 hours ago
I see, okay, I understand now. Thank you very much for explaining that in detail!