Impact of sVDEV on rsync vs. L2ARC

[Dice]

So if I'm following it right this time, that means I've had 3/4 of a million hits on L2ARC, saving me reads from the pool... actually pretty good (even if I was hoping for better and still don't quite understand how it can happen if ARC is under its maximum size).

All at the cost of 15MB of ARC and just over 10GB of L2ARC SSD space.

Hello!

Can I request a follow up on this experiement?
Are you still using this configuration to satisfaction, or has some other insight emerged?

Cheers!

 

[sretalla]

Can I request a follow up on this experiement?

Sure.

Are you still using this configuration to satisfaction, or has some other insight emerged?

Yes.

TrueNAS/FreeBSD 13 provides a slightly different arc_summary report, but the picture looks like this:

Code:

L2ARC size (adaptive):                                          59.6 GiB
        Compressed:                                    19.2 %   11.4 GiB
        Header size:                                    0.3 %  210.0 MiB
        MFU allocated size:                            32.3 %    3.7 GiB
        MRU allocated size:                             1.8 %  216.1 MiB
        Prefetch allocated size:                      < 0.1 %  445.5 KiB
        Data (buffer content) allocated size:         < 0.1 %    6.0 KiB
        Metadata (buffer content) allocated size:     100.0 %   11.4 GiB

L2ARC breakdown:                                                    8.8M
        Hit ratio:                                      8.1 %     718.5k
        Miss ratio:                                    91.9 %       8.1M
        Feeds:                                                    412.1k

 

[sretalla]

For those folks interested in this topic, this other thread would be of high interest too:

ZFS "ARC" doesn't seem that smart...

Without yet resorting to adding an L2ARC, is there a "tuneable" that I can test which instructs the ARC to prioritize metadata? I upgraded from 16GB to 32GB ECC RAM. Yet there is zero change in this behavior. This keeps happening: I run regular rsync tasks from a few local clients, which is...

www.truenas.com

Seems there's the possibility of just keeping stuff in ARC in the first place.