I've been thinking about how to set up a fusion pool, as I've discussed in my last thread where I asked about PCIe adapters. My conclusion there was to wait, but I'm now reconsidering because if I'll want to do it anyway later, I'll get better results if I bite the bullet now than if I add it when the metadata has already been written to the pool because ZFS won't move it all to my shiny new special vdev.
I definitely want to have the special vdev on a three-way mirror of NVMe's on a PCIe adapter card. But now I'm not sure what NVMe's to use.
I do want to do everything I reasonably can to protect myself against failures, short of using a high availability cluster. My chassis has redundant PSUs, currently plugged into the same second-hand UPS (with new batteries, but it does make a disconcerting buzzing noise at times). Down the road as I will actively use it for my small business I plan to also have a second UPS just in case one of them fails, but that's a while away. Irrespective, there are still things that can fail between the UPS and NVMe's, and if my motherboard fails I'd rather not have to rebuild a pool at the same time because the metadata got corrupted. I guess because I've already paid a lot of attention to safety in other areas I also want to protect the metadata vdev as best as I can.
So I'm thinking that I'd like to use SSDs with integrated power loss protection so that I lower the risk of corrupted metadata in the event of a power outage. My PCIe adapter card can only take up to M.2 2280 SSDs, which are extremely hard to come by with PLP. So far I've only found two that don't cost real enterprise money:
- Micron 7300 PRO Enterprise 480GB for around $180 (1.1 PB TBW)
- Kingston DC1000B 480GB for around $120 (475 TB TBW)
However, I've read bad things about Micron SSDs, and the Kingston DC100B is marketed as a boot drive, so really designed for lots of reads and few writes with a max. write speed of 550MB/s, so I'm not sure they would even work for a metadata vdev. Edit: just realized that the Micron SSD only has a write speed of 400MB/s, so while that's still faster than the HDDs, I wonder if it's too slow as a special allocation device.
If those are the best options I can come up with, I feel like I've got something wrong.
Does anyone have a better recommendation? Am I wrong in thinking that PLP is important for metadata SSDs? Where is my mistake?
I definitely want to have the special vdev on a three-way mirror of NVMe's on a PCIe adapter card. But now I'm not sure what NVMe's to use.
I do want to do everything I reasonably can to protect myself against failures, short of using a high availability cluster. My chassis has redundant PSUs, currently plugged into the same second-hand UPS (with new batteries, but it does make a disconcerting buzzing noise at times). Down the road as I will actively use it for my small business I plan to also have a second UPS just in case one of them fails, but that's a while away. Irrespective, there are still things that can fail between the UPS and NVMe's, and if my motherboard fails I'd rather not have to rebuild a pool at the same time because the metadata got corrupted. I guess because I've already paid a lot of attention to safety in other areas I also want to protect the metadata vdev as best as I can.
So I'm thinking that I'd like to use SSDs with integrated power loss protection so that I lower the risk of corrupted metadata in the event of a power outage. My PCIe adapter card can only take up to M.2 2280 SSDs, which are extremely hard to come by with PLP. So far I've only found two that don't cost real enterprise money:
- Micron 7300 PRO Enterprise 480GB for around $180 (1.1 PB TBW)
- Kingston DC1000B 480GB for around $120 (475 TB TBW)
However, I've read bad things about Micron SSDs, and the Kingston DC100B is marketed as a boot drive, so really designed for lots of reads and few writes with a max. write speed of 550MB/s, so I'm not sure they would even work for a metadata vdev. Edit: just realized that the Micron SSD only has a write speed of 400MB/s, so while that's still faster than the HDDs, I wonder if it's too slow as a special allocation device.
If those are the best options I can come up with, I feel like I've got something wrong.
Does anyone have a better recommendation? Am I wrong in thinking that PLP is important for metadata SSDs? Where is my mistake?
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