Samsung xp941 as ZIL...am I crazy or onto something?

[whitey]

OK, so I had this crazy thought early this morning dating back to my investigations of ZIL devices when I first ventured into ZFS whitebox SAN building. Initially high end devices like the STEC ZeusRAM and DDR-Drive X1 looked like good candidates. I have the ZeusRAM and cant say enough good things about it. The DDRDrive-X1 was of course a PCI-e interface, required external pwr, seemed less attractive to HA env's compared to the ZeusRAM w/ dual ported sas and backplane pwr. Time marches on...then I saw these Samsung xp941 devices and know of the M.2 NGFF PCI-e adapters and thought to myself 'DANG would this be a good screaming fast ZIL candidate'? I know traditionally we look for capicators and pwr loss protection in these write cache optimized ZIL devices w/ low latency being a must. Obviously Intel DC s3700's would be a good option as well but my focus is on the xp941 specifically. You woudl still of course be limited to the PCI-e architecture/interface not playing nice in HA SAN/env setups but for an AIO would be a killer @ roughly 10% the cost of a DDR-Drive-X1 ($150 for a Samsung xp941 128GB stick and M.2 NGFF PCI-e adapter v.s. $1500 DDRDrive-X1). A 128 GB xp941 would certainly suffice as I rarely see my 8GB ZeusRAM peak a few GB of use even on the heaviest of workloads.

Thoughts/advice/2cents? Am I out on a limb here?

Assuming this may be unsafe as no capacitor/pwr adapter and data loss may occur...sorta like a poor man's 'turn off sync/disable ZIL' trick...force to RAM...may squeeze more perf but risky.

I know someone on here can explain this WAY more technically than I can...I understand the concept just elegantly struggling for the proper words to cross my fingers.

Maybe gea or dba can weigh-in.

 

[Patrick]

The XP941 has great sequential numbers but essentially looks more like a fast SATA drive on smaller file size writes. It also has relatively low endurance. If you are over provisioning to get better consistency and more endurance, then one can take a 400GB S3700 and over provision it to 100GB and save quite a bit of money in the process.

 

[whitey]

Thanks for weighing in Patrick, yeah I figured an Intel DC s3700 100GB or 200GB for the perf bump may be the way to go for a 'cost-effective' modern ssd ZIL device. Interesting thought on the overprovisioning, not sure I fully follow. Do elaborate as I just snagged a s3700 400GB a week or so ago off 'the bay'. Do you mean partition it into 4 100 GB partitions in *nix/ZFS and then use each for a 100 GB ZIL device for 4 pools?

 

[capn_pineapple]

format it to a single 100gb partition and use that as sole zil device. you've then got 300GB worth of overprovisioning which will give you a very long time before the drive fails.