Zil/L2ARC recommendations for Freenas Mini XL Plus

[JohnBacc]

Just purchased the FreeNAS mini xl plus with 10gbe. I'd like to maximize throughput on the 10gbe network supporting a Mac and PC(both have 10gb cards to a 10gb supported switch) to the FreeNAS mini.
Background/Details:

• Purchased to support a wedding photography business
• Editing on either the Mac or PC system with SSD drives
• Will move Lightroom Catalog and raw images to the FreeNAS mini. There will be times when it will be moved back to the local PC or Mac for additional editing etc.. Each Wedding contains a lightroom catalog and Raw images.
• Approximately 120gb of images for each wedding at a time to be moved
• Depending on the camera used, each raw image between 16 and 100 megabytes to give you an idea of file size. There are also a lot of small files within the lightroom catalog. The catalog is essentially a self-contained database that references the raw images.

To maximize read and write throughput on the 10gbe network, do you have recommendations on the ZIL and L2arc drives I should purchase. This is for the Freenas Mini LX Plus.
Thanks for your help in advance!

 

[Spearfoot]

A ZIL SLOG device is not a cache and will only slow down your data transfers. They're really only applicable to enterprise-level critical systems like virtual machines.

You're better off maximizing your system's memory before considering adding an L2ARC device. If your throughput is inadequate after doing so, you can think about adding an L2ARC, but chances are you won't benefit from one.

 

[Constantin]

Spearfoot, please allow me to politely disagree - it all depends on the use case. For my little NAS (similar to a XL+, 8 drives, Z3), the addition of L2ARC made a huge difference in terms of browsing speed and rsyncs. Granted, I tuned my L2ARC to be metadata only (somewhat similar to the coming TrueNAS fusion pools, I guess) and Lightroom may or may not treat the data similarly to my finder / rsync use case. However, provided that the OP has enough RAM in the server, there is no harm in trying out a L2ARC. My metadata-only L2ARC is 1TB for 40TB of usable space.

As for a SLOG, my system is slow by definition due to only one Z3 VDEV being in use. Faster writes likely require multiple VDEVs in a pool to come close to maxing out a 10GbE connection unless the drives in question are all fast flash. For a small operation It's probably more cost effective to set aside a SSD-based flash pool for initial storage and RAW processing (a DAS via Thunderbolt comes to mind) followed by using the NAS for longer-term backups.

EDIT: One thing to keep in mind is that L2ARC only becomes "hot" after multiple read passes. As of FreeNAS 11, every reboot flushes the L2ARC and it has to be rebuilt. There is talk about making the L2ARC persistent in future versions. Along the same lines, the fusion pools in the V12 TrueNAS future will allow SSDs to supplement HDD-based pools by storing metadata, for example.

 

[Yorick]

I can see the use case of a metadata-only L2ARC when there are a lot of files, that need to be moved in bulk. That doesn’t seem to be the use case here. And you are right, no harm in trying it out.

To the OP, since you are writing from Macs (SMB, right?), your choices are:
- best speed lowest cost - force sync off on the SMB service freenas-side. If FreeNAS has a power outage, your last few writes might be gone. Just - copy again, for your use case, this seems fine
- high(Er) cost and low(er) speed - keep the mac sync write on and add a cap-backed slog. This will be an optane most likely. In case of power loss, all writes will have been done - and what does it matter, the file is still partial and has to be copied again. No real gain over no slog.

@Constantin is right that your write speed will be capped by the drives, not the network. Since you are editing local and then copying over for archive, that’s likely acceptable. The only way to max out that 10Gb link is more vdevs of spinning rust, or ssd mirror vdevs.

Thinking of meta data: man, fusion pools, so righteous. It’s not my use case, I’ll never need it, and I’m still stoked for it coming.

 

[JohnBacc]

Thanks for the feedback--greatly appreciated! I'm just trying to get the best performance possible with this system. I've been looking at FreeNAS for years, but never pulled the trigger, until now. The FreeNAS Mini is a great starting point. I think what I'm hearing is to max out the RAM. The system comes with 32gb, so will max that out. I'll first go without the L2Arc, but that looks like something I may try very quickly.

Knowing the limitations of the FreeNAS min lx plus, what drive do you recommend for the L2Arc. I noticed that the board does come with M2 at least on it, but may not matter in this system--juice not worth the squeeze?

In addition, I'm wondering about 2 SSD's mirroed. Move the files there in a vdev. Could create an iscsi and edit live from the freenas? Thoughts? since its processor-intensive, may not work well on this machine.

Thanks guys!

 

[Constantin]

My motherboard uses a slower mSATA drive for L2ARC and a faster x4 PCIe slot for the SLOG. Even a SATA-connected SSD ought to do just fine for L2ARC given the respective speeds of SATA vs. SSD.

I’d research carefully what can be placed in that m2 slot. If it’s just mSATA, I’d use it for L2ARC. If it’s pcie 3.0x4 i would reserve it for potential SLOG use. At pcie 3.0x2, i consider it a toss-up because modern / fast SLOG drives run at 4x and hence will be handicapped.

Iirc, the current xl+ ships with a c3xxx processor so that should result in a slower m.2 slot.

 

[JohnBacc]

My motherboard uses a slower mSATA drive for L2ARC and a faster x4 PCIe slot for the SLOG. Even a SATA-connected SSD ought to do just fine for L2ARC given the respective speeds of SATA vs. SSD.

I’d research carefully what can be placed in that m2 slot. If it’s just mSATA, I’d use it for L2ARC. If it’s pcie 3.0x4 i would reserve it for potential SLOG use. At pcie 3.0x2, i consider it a toss-up because modern / fast SLOG drives run at 4x and hence will be handicapped.

Iirc, the current xl+ ships with a c3xxx processor so that should result in a slower m.2 slot.

Thanks for the clarification. I don't think I'll push it and will use the connections in place.

 

[Constantin]

I’d research it.

I’d still consider a fast DAS via thunderbolt 3 to import, manipulate, and finalize your work flow. Then push the finished work as a folder to the NAS for long term storage.

There is a Mac software solution out there that allow you to designate certain local folders for upload via SFTP like a Dropbox. That way you don’t even have to babysit the process, the program does it in background for you.