ZFS zil and l2arc on other controller

[Sylhouette]

Hello all

A lot of motherboards these days have six or even more SATA ports. The motherboard we want has two 6Gbps ports and four 3Gbps ports. The rest of the drives we connect to an external RAID card. What if we want to add a zil or l2arc SSD device to the pool, is it wise to put them on the motherboard ports, or is it better to connect them to the RAID controller itself? And if connecting to the motherboard, should I use the two 6Gbps ports for the zil and l2arc SSD drives and use two 3Gbps ports for the OS drives, or is it better to use the 6Gbps ports for the OS and put the zil/l2arc SSD drives to the 3Gbps ports.

Thanks again all for your time.

Regards,
Johan Hendriks.

 

[mav@]

What's about 6Gbps ports, you should just compare benefits. I don't know what are your OS drives, but if they are HDD, hardly they can really utilize 6Gbps bandwidth. Same time, if your SSDs are 6Gbps capable, I would prefer to not create bottleneck there. as zil and l2arc should be as fast as possible and at least faster then main drives to have sense.

What's about choosing controller, I would compare which one I trust more. If external RAID card is expensive, has battery-backed cache and reside on a fast bus -- that's one side. Otherwise, good chipset built-in controllers in AHCI mode could be an option.