Re: btrfs subvolume snapshot performance problem

Hi, I own this SSD :
http://ark.intel.com/products/66250/Intel-SSD-520-Series-240GB-2_5in-SATA-6Gbs-25nm-MLC

I don't think it's a pile of crap :P

So basically, I could remove the discard option inside my /etc/fstab
and I should run fstrim when I have the time.

Maybe someone should update the btrfs wiki and write something about
the discard situation. I tought that I had to use this option to save
some lifespan for my SSD.

2012/12/18 cwillu [off-list ref]:

On Tue, Dec 18, 2012 at 7:06 AM, Sylvain Alain [off-list ref] wrote:

quoted

So, if I don't use the discard command, how often do I need to run the
fstrim command ?

If your ssd isn't a pile of crap, never.  SSD's are always
over-provisioned, and so every time an erase block fills up, the drive
knows that there must be one erase-block worth of garbage which could
be compacted, erased, and added to the pool of empty blocks.  The
crappiest ones only do this as needed (which is why their write speed
plummets with use), and really benefit from people forcing the issue
with -o discard or occasional fstrim.  Everything else should get
along fine without it, although an occasional fstrim certainly won't
hurt: it just shouldn't help much.

quoted

I found this thread : https://patrick-nagel.net/blog/archives/337

It's worth noting that there's a large number of very effective tricks
that an ssd can perform to almost completely negate the caveat
mentioned there.  It really is a solved problem in a modern ssd.

-- 
Salut
alp
Sylvain