Bernd Walter ticso at cicely7.cicely.de
Sat Feb 23 14:39:37 UTC 2019

On Fri, Feb 22, 2019 at 11:47:37AM -0600, Karl Denninger wrote:
> On 2/22/2019 11:24, David Cornejo wrote:
> > on the use case - sometimes the reason is "why not?" - the whole idea
> > of running FreeBSD on such low power hardware is of dubious utility,
> > but it is seriously cool to be able to carry a FreeBSD server in my
> > pocket.
> >
> True but there are some bad assumptions that people can be led to
> believe.  One of them is that ZFS is somehow "more robust" in a
> non-power-protected single-provider NAND-flash based storage system.
> Uh uh.  Yes, a scrub (or just checksum check on the read) will catch the
> "aw crap!" situation where write amplification and read/rewrite hoses
> you during a power failure but there's nothing zfs can do to fix it
> since there's no second copy available.  If the file that gets hit by
> that read/rewrite hosing is /boot/kernel/kernel (or a required .ko, say,
> zfs.ko?) then the system still doesn't boot at all.

Well, first ZFS can do duplicates.
It does so for metadata anyways and with copies property with content as
Nevertheless it is not unlikely that all copies fail at the same time when
using NAND-flash storage, as they are writen at the same time and might get
stored in the same physical blocks.
But after all you can mirror and ZFS write pattern is less stressfull
for flash based media.
I'm using ZFS for USB sticks of any brand since a long time.

B.Walter <bernd at bwct.de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.

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