Need 1 additional SATA port, PCIe recommendations?

[Rico Viqueira]

Background
I have freenas 9.10 Stable running on my bare metal server, specs below. I would like to increase performance by adding ZIL and L2ARC caching to the Volume. In keeping with what I've observed are best practices of mirroring the ZIL I am short 1 SATA port on my board since this would require 3 SSD's. (which I have, 3xSAMSUNG PRO 840 250GB)

To give some background on why I want to do this, I run 1 ESXi datastore via iSCSI for a home lab to test applications and would like to increase performance to VM's with their storage on this datastore.

Other uses I have for this NAS include PLEX jail, and CIFS/AFP shares with personal data on it.

Question

• What cheap HBA/PCIe SATA Controller could I accomplish this with?
• Would something like http://www.newegg.com/Product/Product.aspx?Item=N82E16816124045 work? I really want to avoid expensive controllers and would love to not mess with flashing/cross-flashing. I went through some hell on a LSI 9211 on a different box when going to P20 IT firmware.
• Which of the 7 drives I have be best suited to be placed on this proposed card? (or does it even matter)

Current Hardware

• SUPERMICRO MBD-X10SLL-F-O
• Intel Core i3-4170 3M Haswell Dual-Core
• Mushkin Enhanced Proline 32GB (4 x 8GB) 240-Pin DDR3 UDIMM ECC DDR3 1333
• 4xWD RED 3TB (in a Mirror/Stripe) (6TB Usable) (All attached to this board's on-board SATA 2 ports.

Want to add

• 3 Samsung Pro 840 SSD's for L2ARC and Mirrored ZIL (but only have 2 SATA3 ports left on the board)

 

[Robert Smith]

Be careful with cheap controllers, you do not want ZIL to flake out on you.

How about replacing 4 x 3 TB, with 2 x 6 TB ( or 3 x 6 TB for more redundancy), or even go with 8 TB disks for even more storage (they just came down in price recently).

 

[Rico Viqueira]

Be careful with cheap controllers, you do not want ZIL to flake out on you.

How about replacing 4 x 3 TB, with 2 x 6 TB ( or 3 x 6 TB for more redundancy), or even go with 8 TB disks for even more storage (they just came down in price recently).

Thanks, I was thinking about moving one of those 3TB drives to that controller and keeping the ZIL Mirror on the two SATA3 ports on the motherboard and using one of the SATA2 ports for the L2ARC.

 

[Ericloewe]

A few points:

• L2ARC is dubious with less than 64GB of RAM
• Since it isn't a production environment, sync writes can be a bit excessive.
• If you really want sync writes, there's little point in mirroring the SLOG, since you'd need a simultaneous dirty shutdown and SSD failure.
• SLOG without power loss protection is silly. At that point you might as well drop the sync writes.

 

[Rico Viqueira]

A few points:

• L2ARC is dubious with less than 64GB of RAM
• Since it isn't a production environment, sync writes can be a bit excessive.
• If you really want sync writes, there's little point in mirroring the SLOG, since you'd need a simultaneous dirty shutdown and SSD failure.
• SLOG without power loss protection is silly. At that point you might as well drop the sync writes.

Thanks, I've thoroughly gone through the powerpoint compliments of cyberjock and really just wanted to see what type of performance gains I could get with L2ARC. My performance really isn't "bad" considering the Mirror/Stripe config of the Red's, but it's more cause I wanted to see what this could do. Nothing I have on here this NAS is critical and more of a sandbox for me to play with, couple that with 3 of these Pro 840's which I have just sitting and I figured I could do something with them.

 

[maglin]

I have a feeling that with your small array and only 32GB of RAM you would see a potential decrease in performance. You are better off getting more drives to increase the number of vDevs in the pool. Remember to have good performance you want to stay under 30% full.


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[Ericloewe]

Thanks, I've thoroughly gone through the powerpoint compliments of cyberjock and really just wanted to see what type of performance gains I could get with L2ARC. My performance really isn't "bad" considering the Mirror/Stripe config of the Red's, but it's more cause I wanted to see what this could do. Nothing I have on here this NAS is critical and more of a sandbox for me to play with, couple that with 3 of these Pro 840's which I have just sitting and I figured I could do something with them.

Then forget the sync writes. SLOG will always be an order of magnitude or two slower than just writing to RAM.

As for the L2ARC, it'll depend on the specific workload.

 

[Rico Viqueira]

Then forget the sync writes. SLOG will always be an order of magnitude or two slower than just writing to RAM.

As for the L2ARC, it'll depend on the specific workload.

Good advice, I think you guys just saved me a trip to Microcenter tonight... I'll skip the SLOG and just experiment with one for L2ARC to see if it gets me anything.


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[Stux]

Mirroring slog is no longer required as the pool can withstand a slog failure.

*if* slog fails *and* system fails simultaneously, then at most you should lose just the last transaction group. If you're a bank or other transaction oriented business this could be a problem. If not, it probably isn't.

These days you can also consider PCIe/m2 SSDs for l2arc. They don't need a Sata slot and performance can be much greater.

 

[tvsjr]

The solution is simple...
1x Intel DC S3700 or similar - underprovisioned - SLOG
1x some sort of decent, big drive for L2ARC

Make sure your pool hasn't exceeded 50% utilization.

 

[Rico Viqueira]

The solution is simple...
1x Intel DC S3700 or similar - underprovisioned - SLOG
1x some sort of decent, big drive for L2ARC

Make sure your pool hasn't exceeded 50% utilization.

I like the MLC drive recommendation as this is in line with all guidance for SLOG I've seen. As for the underprovisioned direction you mention. Where is this configuration done? Through manual volume configuration?

 

[tvsjr]

Search it - "underprovision" or "underprovisioning" should find several. There are different options for different drives... typically, just creating a small partition (10GB or so... you'll find threads that help you identify how large the partition should be) is sufficient. Your goal is to give the drive lots of empty cells to use for wear leveling, since SLOG service is hard on a drive.

Pay close attention to the write endurance of whatever drive you select. The 840 Pros you listed are rated at 40GB/day for 5 years, "client" use only (http://www.samsung.com/global/busin...loads/DataSheet-Samsung_SSD_840_PRO_Rev12.pdf - see weasel-words on page 3), or 71TB. The S3700/S3710 is rated at 10 drive writes per day for 5 years. For a 200GB drive, that's 2TB/day or 3.65PB (3650TB).

 

[Stux]

Search it - "underprovision" or "underprovisioning" should find several. There are different options for different drives... typically, just creating a small partition (10GB or so... you'll find threads that help you identify how large the partition should be) is sufficient. Your goal is to give the drive lots of empty cells to use for wear leveling, since SLOG service is hard on a drive.

Pay close attention to the write endurance of whatever drive you select. The 840 Pros you listed are rated at 40GB/day for 5 years, "client" use only (http://www.samsung.com/global/busin...loads/DataSheet-Samsung_SSD_840_PRO_Rev12.pdf - see weasel-words on page 3), or 71TB. The S3700/S3710 is rated at 10 drive writes per day for 5 years. For a 200GB drive, that's 2TB/day or 3.65PB (3650TB).

Two of the maximum size tan action groups.

A transaction group is normally 5 seconds of buffered writes.

If you have 10gbe then you can do 1GB/s for 10 seconds, which is 10GB

 

[Spearfoot]

I like the MLC drive recommendation as this is in line with all guidance for SLOG I've seen. As for the underprovisioned direction you mention. Where is this configuration done? Through manual volume configuration?

Yes, if you want to overprovision the SLOG device you will have to do so manually as the FreeNAS GUI does not provide a means for doing this.

I used these instructions at Thomas-Krenn to configure my Intel S3700 SLOG device, but there are numerous tutorials on the web. A size of 8-16GB is suitable, depending on your system.

@tvsjr is correct about write durability of the SLOG device being important, as are low latency and battery/capacitor power backup as well. An Intel DC S3700/S3710 SSD is a good entry-level choice, and the larger capacity drives have faster I/O though you won't need the space.