Hardware Spec Sense Check

[Programming Machine]

I'm planning a small light use free nas server and wondered if people could sense check my build?

Case: Silverstone DS380.
Motherboard: ASRock C2750D4I (C2750 Avoton with 12 SATA ports)
RAM: 64GB SSD
OS: 512GB Samsung 850 Pro SSD
L2ARC: 2 x striped 512GB Samsung 850 Pro SSD to give 1TB total.
Storage: 8 x 6TB Seagate SATA NAS drives in ZFS2 to give 36TB of storage.
Add in card: USB 3 + eSATA + firewire (optional) - any recommendations?​

I have a lot of duplicate data so want to run deduplication. I suspect the RAM won't be enough which is why I've specified the striped SSDs. I am not too worried about read/write performance. I am a little worried about the risk of corruption with deduplication (it will be on UPS). I'd also like to run encryption - will I need to supply a password at boot up?

I've read different things about the motherboard, have the problems been ironed out? Is connecting the 8 drives through different controller chips (with different SATA speeds) a bad idea? Can anyone recommend a good ECC memory supplier? Does anyone know if the motherboard supports hardware disk encryption (for the SSDs)?

Any recommendations on the USB eSATA add in card for connecting external drives? It is for taking backups into the system from hard disks. There's loads of cheap cards on eBay, but I want something reliable. Has the FreeBSD USB 3 problem been fixed?

Is the striped L2ARC SSDs overkill?

I don't believe I need a ZIL.

Thanks for any help,

T.

 

[SweetAndLow]

Why do you have a ssd for ram?
Why do you have a 512GB ssd for the is? You only need a 16GB USB stick. Your add in cards won't work. You probably won't see a performance improvement by using a l2arc. Your data probably doesn't dedup as well as you think it does and you will need way more memory, like 96GB+.

 

[Ericloewe]

On the off chance you're not a troll (you sure check several boxes...):

• Motherboard is fine, but only Intel SATA ports are reliable right now. ASRock is working on the Marvell controllers.
• 16GB UDIMMs are painfully expensive. If you need that much RAM, wait for Xeon-D or get a Xeon E5 v3 system.
• Samsung 850 Pro for the OS? How about you read the hardware sticky for an idea of what's reasonable?
• L2ARC is massively oversized for this amount of RAM and of questionable utility.
• Dedup is a fantastically bad idea in nearly every case. Dedup it manually at the file level if you must and stick to compression.
• There is no such thign as "ZFS2". You probably mean RAIDZ2.
• Keep in mind there are other sources of overhead. 80% maximum fill, for instance.
• USB 3.0 should work on that hardware, but it's still discouraged. eSATA works fine (if the controller is properly supported, which is only true for Intel, basically), but is strictly limited to 1m total cabling. Firewire is obsolete.
• Encryption is designed to fail by locking the data safely away from others' eyes. Only use it if you must protect the secrecy of what you're storing at all costs. Yes, you must supply the password on boot. There are also other hoops to jump through.
  
• Different controllers/speeds are no problem, if they all work well individually. See above.
• Choose RAM from the QVL. Crucial CT102472BD160B, for instance.

 

[Programming Machine]

Thanks for the feedback.
To answer the first reply I'm using the SSDs as 'Ram' because I don't believe 64gb of DRAM is enough to dedupe 36TB of data.
Encryption is kind of required.
I've considered writing my own file deduping functionality - unless someone can recommend an off the shelf solution?

I could buy an HBA and avoid the marvell. Something like an LSI. What is worth going for? I could then change the motherboard for an amd apu fm2 one but i'd loose ecc. I'm guessing that's vbad?

 

[titan_rw]

If your dedupe tables don't fit into ram, you will be unable to import the pool in the event of an unclean shutdown. So be prepared for data loss if you're going to use l2arc as ddt spillover.

Also as people have mentioned, l2arc is a very bad idea until you have a bare minimum of 64 gig of ram as the l2arc steals space from main memory. And even then it's only recommended to use 5:1 l2arc:arc. So to properly support 1tb of l2arc, I'd look at 256 GB of ram. With only 64 gig of ram I'd limit yourself to 256 GB of l2arc. But keep in mind simply adding this l2arc takes memory away from ARC, which means you have even less ram for dedupe tables to fit into.

Unless you know your data dedupes extremely well, don't dedupe. And then even if you do, keep an eye on the number of blocks in the dedupe tables. For example, I'm using about a gig of ram for my dedupe tables, in a system with 24 GB total. And being that dedupe table data is metadata, and I think metadata is limited to 1/4 of your arc, I'd want to limit your ddt's to 1/4 of your ram to be safe.

 

[cyberjock]

SSDs are not and cannot substitute for RAM. Ever. You are correct that 32GB of RAM won't dedup 36TB of data. So either start off with something like 256GB of RAM, or give up this dream of using dedup to begin with.

No clue what your plan is with dedup, but I'm guessing you haven't actually tried to use it exactly how you intended and are going to find out that your dedup value isn't that great. Aside from one case, I've never seen a dedup value above 1.10x.

If you've done work with dedup, you should know not to bother trying to dedup that much data as the ddt table gets so big that you end up with a CPU that is running at 100% load all the time because it can't process the ddt entries fast enough in RAM. dedup is great for small amounts of highly duplicated data. That is it. Anything else is either not feasible (you can't buy enough resources at any price) or stupid (the resources you need come at a price point with 5 zeros after the dollar sign so you can save a few hundred dollars on extra disks).

 

[Programming Machine]

Thanks for all the advice. Looks like I'm going to have to give up on dedupe, which means I'm no longer wedded to that motherboard (which I chose because it supported 64GB or RAM). Given all the problems I'm seeing with the marvel controllers I'm pretty happy to cross it off my list. The problem is that I'm having a hard time finding a (non extended) mini ITX board that supports ECC memory (I still assume this is a very good idea?) and 9 (8 minimum with USB stick) SATA drives - either on board or through an HBA in a slot. Does anyone know of such a beast? I'd like to stick with chosen case.

 

[Programming Machine]

Okay going on the sticky hardware advice I will probably go for a SuperMicro A1SAi-2750F (better brand than the ASRock with the same number of reliable SATA connectors) with a M1015 (I guess the LSI 9211 is just a more expensive version of exactly the same card (flashing asside)?).
Thanks for everyone's patience with this. You've saved me from making an expensive mistake.