jhoff80 87 Posted February 19, 2018 Share Posted February 19, 2018 My current setup is that I've got an LSI SAS/SATA PCIe 2.0 x8 addin card in my server that supports 16 SATA drives connected to it. My OS drive is connected directly to the motherboard SATA. There's a board I'm looking at that has only a PCIe 2.0 x2 (electronically - physically it's an x16 so that's not an issue). I know that x8 should give 4000MB/s throughput, and obviously x2 would drop that to 1000MB/s. And SATA maxes out at 6Gbps, but that's more theoretical than anything else. I've got a mix of older and newer 5400 and 7200rpm drives connected. Overall though, anyone have any idea what type of real-world implications that would cause? The reason I ask is that I've been looking into new options for the CPU/motherboard both for power-savings and also for HEVC hardware decode. One of the really interesting options is one of the new Gemini Lake boards that should be hitting stores soon. Full hardware encode/decode for HEVC main10 via QuickSync, and also just 10W of power usage. But I don't know if the slowed storage speeds would be worth it or if they'd even be noticeable in a media server environment. Link to comment Share on other sites More sharing options...
Swynol 375 Posted February 23, 2018 Share Posted February 23, 2018 personally i wouldnt do it. running a x8 card in a x2 slot will probably give you issues if it even works at all. I thought the LSI x8 cards only support 8 drives? 4 per mini SAS connector? you can get x4 LSI mini sas cards that work at SATA1 speeds which would probably be more happier to run at x2 speeds. Link to comment Share on other sites More sharing options...
Guest asrequested Posted February 23, 2018 Share Posted February 23, 2018 There are LSI cards that support 16, but I agree, using one in x2 slot is not a good idea. Having only 2 lanes could create a bottle neck. Link to comment Share on other sites More sharing options...
jhoff80 87 Posted February 23, 2018 Author Share Posted February 23, 2018 personally i wouldnt do it. running a x8 card in a x2 slot will probably give you issues if it even works at all. I thought the LSI x8 cards only support 8 drives? 4 per mini SAS connector? you can get x4 LSI mini sas cards that work at SATA1 speeds which would probably be more happier to run at x2 speeds. The card I have has 4 mini SAS connectors. PCIe is (supposed to be at least) backwards compatible so I'd think it would just hit bandwidth issues if anything, but you're probably both right that it'd be bottlenecked. A post I found on the unRAID forum showed that a PCIe 1.0 x4 card (in theory capable of the same 1000Gbps as PCIe2.0 x2) already limits maximum real-world transfer speed to 80MB/s with 8 drives connected, so it'd end up halved again to 40MB/s or less with the 16 drives. I'm sure I'd rarely have all drives active at once, but for the rare times I did, that performance hit would definitely be noticeable. If only there was a Gemini Lake board with more PCIe lanes.. That 10w max with full 10-bit HEVC decode (and encode) in hardware is just so tempting otherwise. Link to comment Share on other sites More sharing options...
Guest asrequested Posted February 23, 2018 Share Posted February 23, 2018 It's not just reading. When writing to those drives, it would take a long time. Link to comment Share on other sites More sharing options...
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