Advice on SLOG, L2ARC etc

[GusGus67]

Hi folks.
I'm a newbie to Freenas, but I've got a lot of experience of Domestic and small business IT. I'm building a Freenas unit which I will use to store my company data, home data and setup some small VMs for my business. I'm also wanting to go to 10Gbe networking for a few devices I use for my business. (My home is my office location)

I've looked at Proxmox and other ways of virtualising Freenas, but the majority of advice seems to be to run it on bare metal. To that end I've got a
Dell PowerEdge R720 2 x Xeon E5-2670, 128GB RAM and 8 x 6TB 10K SAS 6Gbps drives. It had a Dell H700 mini controller, but I've replaced that with an IBM M1015 flashed to LSI SAS9220-8i IT firmware.

I intend to put 2x 300GB 15K SAS drives in to run the VMs (as advised here https://blogs.serioustek.net/post/2014/06/14/vmware-on-freenas-the-right-way-aspx ), as the remaining 6x 6TB drives are way more than I need for my storage anyway.

I have two SATA connections in the R720, one is connected to a DVD drive at the moment which I don't need. I am now looking at whether I should boot the Freenas from an internal USB, or put it on an SSD. That would leave one other SATA port. The question then is, what should I do regarding SLOG/ZIL/L2ARC?

As I have so much RAM, what will I get away with?

Any advice gratefully received,
Gus

 

[PhiloEpisteme]

I am now looking at whether I should boot the Freenas from an internal USB, or put it on an SSD.

You certainly can use a usb stick but many folks are opting for SSD now since they are much more reliable and relatively inexpensive.

8 x 6TB 10K SAS 6Gbps drives

What chassis are you going to use to keep those drives cool? For many applications it seems folks suggest going with lower rpm drives to decrease temperatures. Pool design can go a long way to increase performance which may mitigate some of the need for high RPM drives. You'll see a lot of folks around here using 5400rpm drives; though, perhaps some use cases justify higher rpms.

SLOG/ZIL/L2ARC

Whether you should buy a device for use as a SLOG or L2ARC will depend on your use case. This isn't something you have to buy now either, you can always build your system without them and if performance is an issue you can look into adding the appropriate devices. There is a lot of good advice about what to keep in mind when considering these two option.

If I am not mistaken you'll want to consider a SLOG device if you're using sync writes and seeing slow performance when doing so.

For the L2ARC lots of folks suggest that you put your money into RAM first, and then check to see your ARC hit percentage is low; if so an L2ARC may improve your performance.

(as advised here https://blogs.serioustek.net/post/2014/06/14/vmware-on-freenas-the-right-way-aspx )

That blog post is from 2014. It suggests using server grade hardware, which is great, but doesn't address any concerns with virtualizing FreeNAS, nor does it mention SSDs or justifying using a SLOG or L2ARC. It may be a starting point for folks doing initial research but you don't need to follow it to the letter either.


Hopefully this helps. I'm curious what other folks have to say about the high rpm drives.