Re: Btrfs scrub failure for raid 6 kernel 4.3

[Duncan <1i5t5.duncan@cox.net>]

Waxhead posted on Sun, 27 Dec 2015 14:59:18 +0100 as excerpted:

> I have a "toy-array" of 6x USB drives hooked up to a hub where I made a
> btrfs raid 6 data+metadata filesystem.

Just noting as an aside comment to the main thread...

While doing this with a "toy-array" for experimental purposes is fine and 
indeed encouraged, do your research and LOTS of testing before trying to 
setup particularly multi-device btrfs over USB for normal use.  There 
have been a number of trouble reports posted for USB connected devices, 
where the trouble simply vanished when the devices were attached via 
(e)SATA.  Apparently various SATA/USB bridge controllers aren't entirely 
reliable, a few USB root hubs likewise (tho the bridge-controllers are 
the most common culprit), and USB itself wasn't really designed for this 
sort of thing, tho obviously many people use it for attaching storage 
today.

Personally, while I might use btrfs on single-device USB attached 
storage, I'd be extremely hesitant to do multi-device btrfs via USB, and 
would definitely test it (VERY!) well before considering it usable if I 
did, as there's just too many ways multiple USB-attached devices can get 
out of sync with each other, breaking the filesystem.

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman