Slog and l2arc and 4K?

[kspare]

Are there some longer term test results on how effective 4K provisioning is?

Long story short I have a box with 2 intel ssds but one is actually an hp and I can’t format it with 4K. So my slog is mirrored and OP but without 4K. This is the box is where we host all our terminal servers, so just trying to justify the cost to buy another proper nvme so I can do 4K. I can’t find anything that shows performance gain.

 

[Chris Moore]

Are you even using SLOG and L2ARC in the workload? Before you discuss buying more, the first question is, do you even need what you have.

 

[kspare]

I’m running 60 terminal servers on the box with 24 12gb sas drives, 256 gb ram and 40gb Ethernet.

The drives are intel p3700, I have a 400gb and 800gb op to 100gb each. And a 1.2gb set to 4K.

My problem is the 80pgb is an hp drive that won’t allow 4K. So before I replace it I’m looking for feed back on how useful 4K is on the slog.

 

[kspare]

Also using nfs not iscsi,

It works great, I’m just looking for every ounce of performance I can get.

 

[Chris Moore]

My problem is the 80pgb is an hp drive that won’t allow 4K. So before I replace it I’m looking for feed back on how useful 4K is on the slog.

I don't recall if the difference was tested, but there have been some performance tests done with SLOG devices. You might look at these threads and see if the information there helps.

Testing the benefits of SLOG using a RAM disk!
https://forums.freenas.org/index.ph...s-of-slog-using-a-ram-disk.56561/#post-396630

Testing the benefits of SLOG
https://forums.freenas.org/index.php?threads/testing-the-benefits-of-slog-using-a-ram-disk.56561

SLOG benchmarking and finding the best SLOG
https://forums.freenas.org/index.ph...-and-finding-the-best-slog.63521/#post-454773

 

[kspare]

Thanks for the links. Let’s skip the new users stuff, I’m not new around here, I’m trying to start a discussion on some advanced tuning with 4K in the slog and l2arc.

 

[Chris Moore]

Let’s skip the new users stuff, I’m not new around here

My apologies. Overzealous copy and paste on my part. Hopefully someone with more experience will be able to add to the discussion.

 

[kspare]

No worries.

I’m trying to figure out some real world results on my side too.

Ultimately trying to create a really high performance box for terminal servers. It’s fast, but there is always room for improvement!

There was a post about enabling 4K on the l2arc and slog, maybe i’ll Just jump back over to that one and reboot it.