Intel Optane P4801X 100GB (U.2 or M.2, maybe with adapter) as ZFS log


New Member
Dec 3, 2020
I would like to buy a log device for my ZFS-filer, so the drive of choice should have power loss protection, high iops rate, low latency. I think Intel Optane P4801X series with 100GB is a good choice for my needs.

This drives are available in U.2 and M.2.

Does anybody have experiences with P4801X in general and can also say something about possible advantages/disadvantages of both versions?

I would prefer the M.2 if there are any significant technical advantages against the U.2 version.

One disadvantage of the M.2 model is, that its as twice as expensive as the U.2 model.
Another disadvantage of the M.2 model is, that it looks like that it is currently not available in europe, so i would have to buy one in the US or somewhere else (which could generate some warranty issues).

I also dont have a U.2 connector, but i just found out, that there are passive M.2 to U.2 adapter cards on the market. For example, one is pictured here at the end of the article. Are there any problems with such an adapter + cable to connect a U.2 drive to a M.2 pcie port?


Well-Known Member
Dec 31, 2010
Beside Dram based options, Optane is simply the best Slog. Among all Optane options the DC48 is the only one with guaranteed powerloss protection (while others like 90x are considered uncritical). While the larger models offer more iops, the 100GB model is a very good choice.

The interface M.2 or U.2 does not matter. This is only a matter of mounting options or needed cables.


Build. Break. Fix. Repeat
Feb 15, 2015
We couldn't tell a difference between the P4801X and the 900P\905P as a SLOG, and use both.
The only time we've been picky on the P4801X is for a mirrored system so both have identical drives.
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