Sharing SLOG devices (striped SSDs partitioned for two pools)

[Elliot Dierksen]

This will likely be a project for next weekend. I am looking at this from a pretty low tech viewpoint. I am happy with having a really fast SLOG device that I can use for multiple pools. The idea of spreading the wear on the SSD makes sense, but the secondary system doesn't get a whole lot of use. I am interested in creating some kind of backup for the primary system on the D2600 pool since it has more than enough space. I will probably do a manually initiated rsynch since I don't want to dedicate the entire pool to be a backup. As best I can tell, that precludes the use of zfs send, but isn't a big deal for me.

 

[HoneyBadger]

Assuming it's fast enough to be shared, share away. Shame the 900p doesn't support the NVMe namespace command set, you could carve it up at the hardware level and even have different QoS levels for each "partition" to alleviate the noisy-neighbor problem that's typical with a shared device.

(Consumers are nerds too, Intel. Give us the fun stuff.)

 

[Ericloewe]

Do the P3xxx or P4xxx support multiple namespaces?

 

[HoneyBadger]

Do the P3xxx or P4xxx support multiple namespaces?

The DC P4510 supposedly will in a "future firmware revision" according to this Intel community post:

https://communities.intel.com/message/566079#566079

But I can't find any concrete evidence that any of their drives currently support it.

 

[Ericloewe]

Ah, the mythical future firmware revision.

 

[Stux]

Optionally you could set the MaximumLBA setting on the drive itself to 24GB

Can you do this without using ISDCT? Because I don’t think the 900p supports it, it not being a Datacenter SSD

 

[HoneyBadger]

Can you do this without using ISDCT? Because I don’t think the 900p supports it, it not being a Datacenter SSD

It doesn't support the sector size change to 4K but I believe it supports the erase/LBA setting options.

Edit from the distant future: it seems that none of the Optane drives support the MaximumLBA setting; Intel claims it isn't necessary based on the different NAND used, so you'll want to manually partition a smaller chunk of space just to avoid making your metaslabs too large. See the earlier posts in this thread on the first page for the detailed instructions on doing that.)