One ZIL for multiple pools.

[Lucas Damaceno]

Hello guys.

Could anyone help me with a question?

I have a Supermicro server that is used for storing VM disks through ISCSI connection on FreeNAS 9.10

Supermicro SuperStorage 5048R-E1CR36L
Intel Xeon E5-2630 v4 Deca-core (10 Core) 2.20 GHz
Avago Megaraid 9300-8i
64GB RAM ECC
2x SSD Intel DC S3520 150 GB
12x 4TB SAS Hard Disk
6x 2TB SAS Hard Disk


So I will use my SSDs mirrored to be an exclusive ZIL cache, is it possible to create multiple partition to share? For example 3 pools 12 disks each(RAIDZ2) using 40GB SSD partition. (Now I have 18 disks however the server has 36 slots available so my server grow up soon. )

Once a pool is already created, is it possible to add ZIL/L2ARC?

Tips are greatly appreciated

 

[Spearfoot]

Hello guys.

Could anyone help me with a question?

I have a Supermicro server that is used for storing VM disks through ISCSI connection on FreeNAS 9.10

Supermicro SuperStorage 5048R-E1CR36L
Intel Xeon E5-2630 v4 Deca-core (10 Core) 2.20 GHz
Avago Megaraid 9300-8i
64GB RAM ECC
2x SSD Intel DC S3520 150 GB
12x 4TB SAS Hard Disk
6x 2TB SAS Hard Disk


So I will use my SSDs mirrored to be an exclusive ZIL cache, is it possible to create multiple partition to share? For example 3 pools 12 disks each(RAIDZ2) using 40GB SSD partition. (Now I have 18 disks however the server has 36 slots available so my server grow up soon. )

Once a pool is already created, is it possible to add ZIL/L2ARC?

Tips are greatly appreciated

You need a separate SLOG device for each pool... trying to divide a single SSD up into several partitions, even were it possible to do so, would be counter-productive: you'd have multiple processes trying to access the SSD simultaneously. The resulting I/O contention would degrade performance.

Regarding ZIL SLOG devices: these need to have particular characteristics: power protection, low latency, fast write speed, and high durability. Though they'll 'work', your DC S3520s aren't well-suited for this purpose. The S3500-series SSDs are optimized for reads; the S3700-series are optimized for writes, which makes them a better choice as a SLOG device. The good, better, and best Intel selections for SLOG devices run sorta like this:

• Good: Intel SSD DC S3700 Series SATA, inexpensive, 10 drive writes per day
  
• Better: Intel SSD 750 Series PCIe, mid-level price, 70GB writes per day
  
• Best: Intel SSD DC P3700 Series PCIe, costly, 17 drive writes per day

All three have the power protection, low latency, fast writes, and high durability you need in a SLOG device.

You can find the S3700 SATA SSDs on eBay all the time, in new condition, often packaged as OEM parts sold by Lenovo or Dell.

And yes, you can add log or cache to an existing pool.

Good luck!

 

[Lucas Damaceno]

Thanks Spearfoot!

Another question.

I already have on the server a NVME Corsair Force MP500 M.2 2280 120GB, so I am thinking to use as L2ARC. Can I share this memory for multiple pools or keep the same ZIL recommendation?