HBA with Expander in TN - A whole book of questions

I am currently looking for an HBA upgrade for my server that is running TrueNAS-13.0-U6.1.

*** Had to butcher the links, because it only allowed me 2, which makes it impossible to explain, sry ***

There are multiple reasons I want to switch to a different/better model than my LSI 9300-16i. First of all, I want to get all my disks on one PCIe slot to avoid possible future problems I may encounter when troubleshooting a virtualized TrueNAS instance on my Unraid server. I split my HBA into two separate IOMMU groups, which were handled differently by the hypervisor. Currently, I have everything scattered over the LSI the onboard HBA (4 Sata, 1x slimsas-> 4x Sata = total of 8) and I even had one of these (apparently dangerous because JBOD) adapters to get another two sata port from the m2 wifi slot. Next to that I was not totally happy with the upgradability/expansion of the system, because I was already on the edge with sata and even pcie ports while not even fully utilizing the pcie bandwidth. With that being said, to clean up my drive mess I want to put all these drives on one single HBA and into an old office computer (something like a 4th gen i7) and test the existing components for a week to ensure long time stability (and avoid bugs created by virtualization).

So, I did a few days of research and figured out that there are basically no HBAs with more than 24 internal ports (through using the SAS/SFF to SATA cables). What I found are the following types of expanders that are apparently being used to multiplex the signal to multiple ports: /www.ebay.com/itm/165350815615

Or this: HBA Expander 2

And after finding these types of products even more questions came up that I didn’t find a definitive answer too:

  1. Is the setup different on TrueNas (this one is easy :slight_smile: ): there was literally no set up for the LSI 9300 I am currently using. So, my guess is the same with eg. this HBA: /www.ebay.com/itm/166481101887 + the Expander card → Just put it in a slot and it works ?
  2. How do I wire these up ? I couldn’t find dedicated wiring diagrams (only YT videos) which explain how to put the expander together with the HBA into a PCIes. According to videos and the official documentation, I did a hypothetical wiring diagram, so how I understand it works like the following:

Basically, I want to be able to attach 32 SATA devices while having spare SFF ports for (potential) U.2 drives. Of these 32 two SATA devices I want to utilize 18 ports with HDDs (2x pools (one x15 + one x2) + a hot swap) and 13 ports with SSDs (1x pool + 1x hot spare) while having one port to spare. Would the wiring work as I illustrated? So basically, my idea was to adapt the one big SFF (8654) to two smaller ones (8087) that are both connected to the expander. I read that these expanders basically work like unmanaged switches. So, my idea was to use the ports as either inputs or outputs on this model, am I wrong with this? In another video I saw that two slots were marked as inputs but not on the two models I linked above. Are there always two inputs? Can Passthrough be a problem?
I only found one source for the SFF 8087 to 8x SATA. Are they reliable/ a potential bottleneck ?: /www.datastoragecables.com/sas/internal/minisas68-satax8/

  1. So talking speeds, assuming I have a lot of HDDs and a bunch of SSDs (as illustrated above), I come up to a needed bandwidth of about 62Gbit/s = 7.75Gbyte/s. While the PCIe Gen 4 x8 slot should have plenty of bandwidth left I am curious about the cables, the expanders and most importantly the SFF 8654 port. Will the system bottleneck when connected to only one SFF 8654 port of the HBA ? Hooking up hypothetically only SSDs would bottleneck the system by 2.25 times by the PCIe (36Gbyte/s needed / only 16 Gbyte/s). Would the number be way lower because of only using one SFF port (so not 1/3 b.c. 3 ports but for example 1/4 of the PCIe speed available) ?
  2. Why only one SFF port ?? → I am currently using (oh boy here it comes) SLOGs, L2Arcs and Dedups for my system to tinker around with. I know this is a big discussion point where lots of experts just say: Avoid it. You won’t benefit from it either way ! BUT I want to make up my own mind on this and I think there is a good chance to see a difference on a system with >30 drives. Especially Dedup has good potential to save a few percents of storage while not losing performance because I only need to compute that I already had on my system (replicated from: /www.youtube.com/watch?v=KjjSJJLKS_s&t=666s.
    I want to use the SLOG for a bunch of other VMs I want to deploy and see if I benefit from it, but rn it is more experimental for me.
    For now, my Dedup as well as my SLOG for the ssd mirror vdevs is placed on two intel optane p900. I didn’t split them on separate devices because I lack the PCI lanes for that. And it would be a big waste of NVME considering the SLOG “only” gets 10Gbit data in. The main problem is that it works well for my mirror vdevs but not my RAIDz2 main storage pool, because I am lacking the 3rd NVME for the redundancy rule. My idea was to switch to these: U.2 SSD
    Which have the same speeds as these: /harddiskdirect.com/ssdped1d015tax1-intel-optane-ssd-905p-series-1-5tb-pci-express-nvme-3-0-x4-hhhl-solid-state-drive.html?srsltid=AfmBOoqnCqqRmN8-O0aVa2a2e5e84q5Xx0heQeDLwXljfk1BEHGSPvb63vQ

But are way cheaper. I could attach these to the left-out slots of the HBA easily with SFF8654 to 4x U2 cables. Could the xPoint/U2 compared to HHHL be a problem? Speeds are the same but what about IOps (ARK says it’s the same if I didn’t see it wrong)? Are these types of drives not suitable for SpecialVDEVS, LOGs, Dedeups ? From what I saw they are good for this use case, but I am not sure.
So, considering the intel U2 drives I could easily expand my SpecialVDEVs while keeping the same, if not higher, integrity layout (potential RaidZ2 or mirror with 4 drives). Next to this the space requirement is also getting big for a capacity up to potentially 150TB for my potential main pool (15x 20TB RaidZ2 x3 approx = 150TB net) with 1GB of Dedup for 1TB space.

  1. Bottlenecks: These LSI cards can actually connect up to 240 Sata devices which even would bottleneck with only HDDs attached (assuming 0,16 GB/s * 240 = 38,4 GB/s > 16GB/s from the PCIe). Not even talking about all SSDs or the supported 32x NVME/SAS devices. In my setup I don’t mind bottlenecks as long as they are symmetric aka all drives are basically relatively bottlenecked to their native speeds. If I would for example attach 4x or even 8x U2 drives over the two left-out SFF8654 and use these under full load in VMs (not the network) and it makes the “Main” hdd storage pool unusable, then this would render the whole idea useless for my case. Has someone experience with the bottlenecks of these cards? How does ZFS/ TrueNAS handle this ? Is it bad for SpecialVDEVs to put them on shared PCIe connections? We are still talking about Gigabytes per second that could be potentially reached for each separate pool and VDEV (so still NVME/PCIe speeds that would be theoretically available).

  2. Another simple one: Do all of these SFF Expanders only need power over PCI ? I don’t have any slots left that is why I want to put this card on an external powered PCI slot. Could that lead to problems? Advice ? Big no-go ?

  3. How can I verify the source/quality of the HBA that I want to buy on e.g. ebay? Can I validate that it is not a cheap dupe? Can I test the hardware myself to verify that ?

  4. Suggestions for alternative ways ? How is my general idea ?

A few more comments:

  • I am currently very restricted with PCIe because I am using Intel consumer CPUs. That is why I want to only use one x8 Gen5/4 slot for all my storage (my guess is there is no Gen5 HBA yet and it will also be unaffordable for me)
  • I want to try out the SpecialVDEVs features of TrueNAS on bare metal by myself and see what I could potentially use long term. I can always switch between no SLOG, Dedup through the use of backup to a second server and a recovery afterwards, while keeping all my data and the file structure. And I will do a backup either way.
  • I would be glad about links/documentation etc. I researched a lot already and want to tick off boxes that potential experts can answer quickly. Sorry, if I overlooked something major, especially in this forum.

I know this is a long post, but I really want to know as much about this type of HBA before I invest in hardware that will cost me hundreds short term (if not thousands long-term) of dollars. I would be glad about any flaws pointed out by experts or better suggestions on how to solve this.

I really found the community very helpful in my last post which is why I came here and didn’t just go to an arbitrary subreddit or other forums.

And btw here is the whole reason for the 1x HBA → a lot of drives story:

Thanks in advance :slight_smile:

Actually the HBA linked above is just a Gen3 HBA which would be way too slow for me. I also saw there are already Gen5 HBAs. Can someone suggest Gen4 & Gen5 HBAs with compatible expanders and also where to buy them ? (Gen5 just for theory - they seem way too expensive)

Too many questions in one post, and still not enough information about your hardware and use case.

But Tri-Mode HBAs are not favoured due their way of running NVMe drives under the SCSI bus. If you want U.2 drives you really should have the corresponding PCIe lanes, meaning a Xeon Scalable or EPYC system.
I also do not like the mention of dedup with consumer hardware, its limited RAM capacity, and a large storage pool.

They need power. Full stop.
Some expanders have a 4-pin Molex and can be powered from that instead of the PCIe bus.

Yea I figured that, but everything was connected in terms of logic and I didnt want to do 4-6 posts just for one HBA that I don’t fully understand. Sorry btw. if that is against community guidlines, I can delte the post if so.

The question is what information is most needed:
CPU: i9 - 13900 for my main server (VM ! good single core perf. needed / Xeon to expensive) - i7 47XX on my test server
RAM: 128GB Main server / 16Gb test server
PCIe layout: 8xGen5; 8xGen5; 4xGen3; 4xGen3 (Asus W680 ACE → again. Server Mobo too expensive for me for NEWER systems)
What else ?

Ok that is good to know, I would love to go with a 32 or 64 core Ryzen but that wasnt in the budget for me, which I obviously regret terms of PCIe lanes but I want to solve that problem with my current hardware and avoid starting off with a whole new CPU, MOBO combination.

May I ask why ? What exact problem did you encounter ? I tried it just a few hours and speeds stayed in the 10s of Gbits over a 10Gbit network. 64Gb of ram was plenty for a testvm and the CPU spikes also weren’t that bad while basically having 3 VMs that only take the spcae of one. Can running them parallel lead to problems ? I am suprised the SLOG wasn’t jumped on first, for the DEDUP I already saw the advantage on my system while trying (not for SLOG yet). Did I miss a major flaw ?

Thanks for verifying.

5.: ANSWER: Found an answer here while talking to a tech guy from ebay that is using the hardware on a daily basis. He mentioned that the controllers use round robin so from what I understand it is fine for SAS & SATA but not for stalled NVMEs. Even worse when the PCIe lanes are bottlenecked, so I will basically use the 3x M2 slots of my MOBO for Oculink adapters and directly attach the U2s. Best “consumer” solution from what I saw for now.

Try reading post by dak180 at link below regarding de duplication and links made on subject.


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Thanks I went half way through for now and the example in this article Dedup is exactly my case ! Only problem, my max theoretical RAM for a Raptolake is 196GB (close to 256Gb) and I would assign something like 128Gb in a real worls scenario.

Why the “x5 save” storage criteria ? Not an expert but that doesn’t make sense. When we are in the magnitude of around 150TBs (also my goal, currently 40TBs), I am glad to have 0.2x (20%) savings and have 30 TB less space usage, potentially hundreds of $ of HDD, thousands of SSD. That would mean Dedup only would work somhow/good/perfect in datacenters with petabytes and upwards and nowhere else ? Is ZFS only targeting these as potential customers ? Highly doubt that.

So the experience about Dedup is very mixed as I see, I will try to do (and also report) a few more tests to see my experience and also the reactions … maybe I did something wrong in my setup.

Not enough money for a “server motherboard” but enough for a W680 “desktop workstation” motherboard that is twice as expensive as its Z690 consumer sibling (higher specifications overall but for ECC support), plus a top-of-the-line-and-accordingly-overprised Core i9? I do not quite grasp that.

Desktop “Ryzen” tops at 16 cores, so 32-64 cores would be EPYC (which is simply referred to by its “Zen” architecture). If the lower maximal frequency of EPYC is still satisfying, the solution would have been to go for second-hand EPYC 7002/7003 or 1st/2nd generation Xeon Scalable rather than current EPYC 800’/9004 or 4th/5th gen. Scalable. With second-hand DDR4 RDIMM rather than DDR5 ECC UDIMM, that could even end out being cheaper for much more RAM.

ZFS dedup is a memory hog. Read and re-read slowly.
With default recordsize, the guideline is 5 GB RAM per data TB—and (much) more with smaller recordsize, as would be the case for VMs. This comes on top of other, basic, requirements.

My experience? I, unwisely, set up a 16 TB dataset with depup within a larger pool, which serves a dumping ground for all the external storage I have lying aroung. It currently holds about 10 TB. The primary NAS for this dataset has 64 GB and an Optane 900p persistent metadata SLOG (I had read quite some documentation, and, typically for a newbie, thought I would get away by piling up ZFS fancy features). The backup system just has 128 GB RAM. Both are pure storage, no VM, no apps.
Result: The primary does fine with its barely minimal RAM for such a setup. The backup does fine as long as it stays at 128 GB; but at one stage I removed half the RAM and then a scrub of the pool would take several days :scream: rather than several hours.
Lesson: The guideline is accurate. 64 GB RAM is not enough to handle a mere 10 TB of deduped data. At an actual dedup ratio of less than 2x, that is an awful lot of ressources thrown in for minimal space benefits.

That’s a sensible guidance given the hardware resources one has to thrown in to make dedupplication viable. Otherwise you’re better just buying more storage space.

…for which you’ll spend ten of thousands of $ for RAM!
40 TB of regular 128k-recordsize data would need at least 256 GB RAM, possibly more to account for your VMs. 150 TB of small record size deduplicated block storage would require several terabytes of RAM. Or several 1.6 TB Optane P5800X (six in two 3-way mirrors?) as dedup vdev to assist a mere helf-terabyte of RAM, maybe? Never mind, it just isn’t worth for ridiculous 0.2x gains.

Wrong guess! Enterprise really is the target market for ZFS.
It’s great that we can enjoy ZFS in our home labs as well, but some exotic features (dedup, dRAID) really only make sense for special applications with mean big iron servers.

Back to basic questions:
How much of (bulk) data? (The kind that would do fine on raidz2/3 at under 70% occupancy.)
How much of VM data? (The kind that really wants mirrors at under 50% occupancy, and quite possibly SSD at that.)
How much RAM for the VMs alone?
What drives do you own already?
Then we can see if there’s a way to fit that in a W680 system.


Just a heads-up.

What is your understanding of ZFS?