Small files performance

[dennisjoh]

I have a FreeNAS server running with Rsnapshot in a JAIL for backups of a number of systems.
One of the systems has about 1.5 Tb of small files (PDF files). These are all followed by Rsnapshot and hard-link via Rsync.

The system specs;
2x Quad CPU
24 Gb memory
4x 8 Tb SATA disks

Is it useful to use a ZIL or L2ARC cache for this?
Or is that not useful for small files?

 

[DrKK]

One uses a ZIL and/or L2ARC when one experiences problems that could be solved with a ZIL or L2ARC.

Are you experiencing a problem?

I can tell you this: You *NEVER* use an L2ARC until your memory is maxed out. Ever.

 

[dennisjoh]

One uses a ZIL and/or L2ARC when one experiences problems that could be solved with a ZIL or L2ARC.

Are you experiencing a problem?

I can tell you this: You *NEVER* use an L2ARC until your memory is maxed out. Ever.

We are experiencing problems with slow copy small files on the same ZFS pool.
1,5 Tb with small files during more then 5 hours.

Memory ARC is using 50% now.

What about a ZIL/SLOG for speed up?

 

[DrKK]

I assume you mean 1.5TiB and not 1.5Tb. Doing the math....

Works out to 92MB/sec, approximately. For small files, depending on the other parts of your system, that's slow, but not impossible. Based on what you've said, I don't think an L2ARC will help you at all, in fact, it will probably make it worse. ZIL, maybe. In my view, the problem is going to be the system configuration. Let's find out: Can you tell us more about your system? Is it virtualized? What CPU and motherboard? What RAM? How is the disk pool configured?

Also you may want to try to read this: https://forums.freenas.org/index.ph...-to-zil-specifically-based-on-my-usage.21271/

 

[dennisjoh]

Server Specs:

Supermicro X8DTL motherboard
24 Gb DDR3 1066 Mhz ECC REG
2x Intel(R) Xeon(R) CPU E5506 @ 2.13GHz CPU
12x 4 TiB SATA 7200 DISk
MIRROR POOL ZFS
Adaptec 6405 controller (JBOD all disks to FreeNAS)
FreeNAS 9.10 on USB

FreeNAS is directly on the physical system.