Best setup for DELL 530 with iSCSI to VMware

[vooze]

Hi
So I’m setting up a FreeNAS box for work for our “not so important stuff” while waiting for our new TrueNAS x20 to arrive.
Specs:
DELL R530 (I had it laying around and it still have Pro Support, so it’s pretty good for second box)
Intel(R) Xeon(R) CPU E5-2630 v4 @ 2.20GHz
64GB RAM
HBA330
8 x 8TB HGST Ultrastar HDDs (is gonna be configured in mirrors)
Chelsio Dual Port 10Gb Ethernet Network Unified Wire Adapter Card T520-SO-CR


We are running a VMware vSphere environment with 3 hosts connecting to SAN switches with all the vmware best-practices.

Now, how to get the best out of my DELL R530.

Therefore, my question is, with my hardware in mind.
- Should I enable compression (lz4) on my zvol? Does it make sense for iSCSI with a CPU with many cores, but low GHz
- Recommended block size for the zvol? Does it matter?
- Will it make sense to buy a SSD for caching?
- Anything else?

Thank you :)

 

[Ericloewe]

Should I enable compression (lz4) on my zvol? Does it make sense for iSCSI with a CPU with many cores, but low GHz

It's probably still worth it. Once zstd compression is in, you'll be able to fine-tune it to better trade off speed and compression (for new data, anyway). Don't forget that everything that's compressed on disk will also be compressed in ARC - if your workload compresses two to one, you effectively double your ARC without adding RAM, which is awesome and will do miracles for performance.

- Recommended block size for the zvol? Does it matter?

It does matter, but it depends. As large as you can tolerate is a good starting point. If your write amplification and wasted space is manageable, I'd suggest 8k.

- Will it make sense to buy a SSD for caching?

That's hard to say. If you don't use sync writes, an SLOG won't do you any good. If you find that your ARC deadlists are getting a bunch of hits, it might be worth adding an L2ARC, but more RAM might help more, first.

HBA330

That one kinda worries me. If it's a PERC h330, you should be able to crossflash to LSI SAS 9300 and it'll be a known, working quantity - probably exactly what iX will ship in your TrueNAS box.

 

[vooze]

It's probably still worth it. Once zstd compression is in, you'll be able to fine-tune it to better trade off speed and compression (for new data, anyway). Don't forget that everything that's compressed on disk will also be compressed in ARC - if your workload compresses two to one, you effectively double your ARC without adding RAM, which is awesome and will do miracles for performance.


It does matter, but it depends. As large as you can tolerate is a good starting point. If your write amplification and wasted space is manageable, I'd suggest 8k.


That's hard to say. If you don't use sync writes, an SLOG won't do you any good. If you find that your ARC deadlists are getting a bunch of hits, it might be worth adding an L2ARC, but more RAM might help more, first.


That one kinda worries me. If it's a PERC h330, you should be able to crossflash to LSI SAS 9300 and it'll be a known, working quantity - probably exactly what iX will ship in your TrueNAS box.

Thank you for your reply!

About the lz4 compression. I seem to recall that having a "slow" CPU hurt it a lot when I was running my previous 25W 1.8GHz Quadcore xeon. But maybe that was just because of the 25W.
The TrueNAS X20 will be running 6 core xeon-D with 2GHz IIRC. So maybe it wont be an issue? Also have not heard about zstd before.

The TrueNAS X20 I'm getting is delivered with a 200GB "Write cache" (says on the invoice) and I know I told them VMware, mirrors, iSCSI etc.. Is that just a SLOG they are talking about?

Also, it's a HBA330, not a PERC330. I'm gonna test it before, but I think it will work from this thread: https://forums.freenas.org/index.ph...-r530-with-a-perc-hba330-work-with-zfs.48532/

When setting up the zvol it defaults to 16K. So it should be fine?

 

[Ericloewe]

Write cache would be SLOG, yes.

When setting up the zvol it defaults to 16K. So it should be fine?

Depends on your workload. You might want to try several settings and compare space usage and speed.

I seem to recall that having a "slow" CPU hurt it a lot when I was running my previous 25W 1.8GHz Quadcore xeon. But maybe that was just because of the 25W.

Could be.

The TrueNAS X20 will be running 6 core xeon-D with 2GHz IIRC. So maybe it won't be an issue?

I'm sure it'll handle whatever workload you asked your rep for. The E5 would probably be faster, though.