Port multipliers on PCIe X1 2.0 SATA expansion card

[The Majest]

Hello everyone! I'm new to the forums but have been running Jellyfin on my old desktop for about a month and am really happy with how it's going so far. However, I'm running out of SATA ports on my Asrock B450m HDV, so I'm thinking of using the PCIe x1 slot to add a SATA expansion card. Since I'm new to large-scale media storage and data hoarding, I have a few questions. Please correct me if I'm wrong!

While researching PCIe SATA expansion cards, I noticed that most controllers come with 2 to 4 ports. However, some manufacturers add port multipliers to extend the number of ports to 6, 10, or more. From what I’ve read, these multipliers aren't popular because they split the bandwidth of the original port. Also that the multiplied ports can't be accessed simultaneously, which might cause data issues (am not too sure of this one). Despite these drawbacks, the idea of extra SATA ports is too tantalizing so, for my peace of mind: Is it a bad idea to use a PCIe SATA expansion card with multiplied ports solely for Jellyfin media storage?

Also I know that PCIe 2.0 has a maximum bandwidth of 500 Mbps, which could bottleneck the drives if more than two 200 Mbps HDDs are running at full capacity. However, based on the info on task manager, even when streaming to multiple devices at 1080p/60 Mbps, the drive workloads seem very low, sometimes close to cero. If I connect, say 6 HDDs, is it even likely that they would hit the 500 Mbps bottleneck when used just for Jellyfin? (FYI: The PC has an old AMD RX580 installed with hardware acceleration enabled, and I have a 300/50 download/upload internet speed).

[Efficient_Good_5784]

It will depend on the OS being used.

If you have a software raid, it will be terrible for a few reasons:

• A data scrub will clog the bandwidth
  
• Might not or will not work with some NAS OS like Truenas
  
• Can be unreliable
  

I would suggest you look at a proper HBA card to connect more drives.

[TheDreadPirate]

I've used this PCIe SATA expansion card in my system and have had zero issues so far.

https://www.amazon.com/gp/product/B09Y1NRHX3

This manufacturer does have a 6 and 10 port model. I had wanted the PCIe x4 model, but my mATX motherboard only had a x1 slot available.

Real world, the PCIe 2.0 1x bandwidth is probably not a practical limitation for serving video in Jellyfin. Even when serving multiple videos you have to consider the disk I/O performance when the disk has to split its time between multiple streams, transcoding performance, etc., when considering what the limiting factor will be.

If you plan on using your drives in a ZFS raid, PCIe bandwidth will definitely be a limiting factor for that. But, again, not a real world limitation.

For my ZFS array, I do connect the drives directly to the board since my use case does significantly benefit from the additional throughput. My drives not in the ZFS array are connected to the expansion card, but I push those pretty hard as well and have yet to encounter any issues.

[The Majest]

Good to know the PCIe slot won’t be a bottleneck for Jellyfin. I’m not planning to set up a drive array or anything advanced right now, but it's useful info for when I upgrade the server later.

Regarding multiplied SATA slots, do you have any details on potential bandwidth issues or if it's true that two drives connected to the same multiplied port can't be used simultaneously? Because I am really tempted to get a 6 port card even if it has a 4 port controller.

[TheDreadPirate]

FYI, you may have noticed that I moved your post from the wrong thread here.

I haven't noticed any issues using multiple drives at the same time.  But one of my drives on the SATA expansion card isn't used a lot.

To test this, I copied a big movie from my ZFS array to my NVMe drive to remove that as a limiting factor and then simultaneously copied the file to both of the drives connected to the expansion card.  The throughput is where I'd expect each to be.

   

[The Majest]

Thanks for moving the post! I was going crazy trying to figure out how to delete it. Maybe I didn’t explain myself well, but when I mention multiplied ports, I’m talking about the difference between the number of ports on the embedded controller and the ports on the expansion card.

For example, your card has an ASM1064 controller that supports 4 SATA Gen 3 ports, which matches the number of ports on your 10Gtek expansion card. But sometimes you get the same 4-port ASM1064 controller with multiplied ports, so the expansion card could end up having, say, 10 physical ports for connecting drives. So i want to know if this kind of port multiplying can generate issues with media streaming.

[TheDreadPirate]

I can't speak to that since mine doesn't have one.

But I'd assume it wouldn't be. People use cloud storage to store their Jellyfin library. If Jellyfin can handle the latency and consistency of cloud storage, it can handle the potential inconsistency of a port multiplier.