Md based tmpfs with zfs root system.

RW rwmaillists at
Wed Oct 18 20:11:43 UTC 2017

On Wed, 18 Oct 2017 12:45:59 -0400
Christopher Sean Hilton wrote:

> Good day,
> I've using a new system with root on zfs. I've traditionally used a
> /dev/md* based tmpfs for /tmp. A little initial reading on the subject
> shows an argument about this practice but I didn't find any threads
> that provide a resolution. 

md devices and tmpfs are two different things. tmpfs is a bit like an
md device, but it has its own built-in file-system, so it only uses
memory for current files, whereas an md device stores all the sectors
that have ever been written to, even if they hold deleted files.

I don't follow ZFS much, but unless there is a specific reason not to
use tmpfs with zfs it's preferred over md devices.

If the issue is the use of swap with zfs, neither tmpfs nor
swap-backed md devices actually require swap.  

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