Re: weird swap device name

From: Nikos Vassiliadis <nvass_at_gmx.com>
Date: Fri, 16 Jan 2026 11:48:04 UTC
On 1/14/26 21:45, Mark Millard wrote:
> FYI for another issue,
> 
> I would never recommend swapping to a file in a file system (vnode),
> especially to a zfs file:
> 
> QUOTE ( https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=206048#c7 )
> On 2017-Feb-13, at 7:20 PM, Konstantin Belousov <kostikbel at gmail.com>
> wrote on the freebsd-arm list:
> 
> . . .
> 
> swapfile write requires the write request to come through the filesystem
> write path, which might require the filesystem to allocate more memory
> and read some data. E.g. it is known that any ZFS write request
> allocates memory, and that write request on large UFS file might require
> allocating and reading an indirect block buffer to find the block number
> of the written block, if the indirect block was not yet read.
> 
> As result, swapfile swapping is more prone to the trivial and
> unavoidable deadlocks where the pagedaemon thread, which produce free
> memory, needs more free memory to make a progress.  Swap write on the
> raw partition over simple partitioning scheme directly over HBA are
> usually safe, while e.g. zfs over geli over umass is the worst construction.
> END QUOTE
> 
> I have in the past suffered such consequences.

That's good to say because everybody is saying that it is not
recommended but most of the time people have no first hand experience of
a failure.

While this system have a few GBs of swap I removed it temporarily and I
used a zvol for swap. When I am done it will have the traditional swap
partition...