Marc Haber posted on Sun, 13 Mar 2016 22:05:37 +0100 as excerpted:

On Sun, Mar 13, 2016 at 05:12:35PM +0000, Duncan wrote:

quoted

Marc Haber posted on Sun, 13 Mar 2016 12:58:10 +0100 as excerpted:

quoted

I see the same metadata spread as with the old filesystem in btrfs fi
df,
totl at 23 and used at 2.38 GiB. What I find strange is that this
filesystem has Data, System and Metadata in "single" profile, is this
the new default for a 200 GiB file system?

Single is default for data.  Metadata (and system) will normally
default to dup on a single device, raid1 on multi-device, EXCEPT on
detected SSDs, where it defaults to single as well, because the
firmware on some ssds will dedup it in any case.  If you know your ssd
isn't one of the deduping ones (as I do, here), you can of course
overrule that by specifying modes at mkfs.btrfs time.

It was both times the same Samsung 840 EVO. Has this SSD detection been
added recently, or did older versions of mkfs.btrfs not detect an SSD
through a crypto layer, maybe?

Btrfs' ssd detection has been there for quite some time now (for 
userspace, since well before the releases synced to kernel version with 
3.12 or so, which effectively makes it ancient history in btrfs terms).

But according to the mkfs.btrfs manpage, the detection is based on 
/sys/block/DEV/queue/rotational (with DEV substituted appropriately), and 
various layers got support for correctly passing that thru at various 
times, some before btrfs, some after.  So that's very likely why btrfs 
didn't detect it originally, if it was on top of crypto and/or some other 
layer that might not have been passing that thru.

-- 
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