Optane for SLOG in older hardware?

[richardm1]

I'm curious about using Optane for ZIL/SLOG in an older machine (a Dell Precision T7600). I haven't been able to sort out the CPU and chipset compatibility constraints with regard to FreeNAS usage. I know these devices are officially meant for use with only 7th gen CPUs and higher but I don't know if this limitation applies to our use case.

Can I buy a small M.2 NVMe Optane, drop it into a $20 PCIe adapter, stick it in a PCIe slot, and profit from speedy ZIL goodness?

 

[Constantin]

I’d review first and foremost whether your rig would benefit a lot from a Optane SLOG.

That turns into a use question, how your pool is organized, what type of hardware, network, and so on. SLOGs by themselves don’t magically speed up all aspects of the pool.

Can you tell us a bit more how you think the rig will benefit?

 

[richardm1]

I'm more worried about it working at all and less worried about how optimal it might be. I haven't built the system yet but I'm thinking I'll benefit from ZIL due to the virtualization workload ("I/O blender"), especially if I choose NFS over iSCSI.

 

[jgreco]

Try turning off sync writes FIRST. This will establish the very fastest that your pool will ever be. Once you put a SLOG device into the mix and turn sync writes back on, speeds can only drop from there.

 

[richardm1]

Let's go with a hypothetical workload that benefits immensely from sync disable. Would an NVMe Optane device work in my older system?

 

[Ericloewe]

It's just PCIe, it works in 99% of scenarios. Is it useful? That's a different question and you really should provide some specifics so that our answers are useful.

 

[Constantin]

The impact of Optane depends not only on the use case, but also the rig it's running in and the model of Optane memory.

Your pool configuration will have a significant impact on the performance - are you optimizing for IOPS with multiple VDEVs in parallel, for example. Then there is the question of the type of storage device (SSD vs. HDDs), networking connection (1GBe, 10GBe, etc.) the capability of the CPU, the width of the PCIe bus, etc. Never mind switching gear, etc. between your NAS and the computer.

There are also significant performance differences between the 16/32 GB generic m.2 NVME modules, vs. the 800 series vs. the P4801x, for example. See the ServeTheHome recommendations for SLOGs and the local SLOG thread for benchmarking. ServeTheHome has yet to test the P4801x but some results are published at the end of the SLOG thread here.

 

[arias74]

I know this is an older thread, but thought I throw my 2cents in.

I've just installed an Optane 16GB NVME drive into a Dell R510 using an M.2 to PCIe adapter, and FreeNAS-11.2-U3 found it without a problem. I've got a RAIDZ2 pool configured with 10 10TB drives, and I've added the Optane drive as an SLOG drive, and it works great. With sync writes set to always, I'm almost able to fully saturate my gigabit nic.

I picked up the Optane 16GB drive off of Amazon for $23. Not too shabby.