XFS and nobarrier with SSDs

[Georg Schönberger]

On 2015-12-14 10:58, Christoph Hellwig wrote:
> On Mon, Dec 14, 2015 at 09:38:56AM +0100, Martin Steigerwald wrote:
>> Is it safe to use XFS (or any other filesystem) on enterprise SSDs with Power
>> Loss Protection (PLP), i.e. some capacitor to provide for enough electricity
>> to write out all data in DRAM to flash after a power loss, with a reordering
>> I/O scheduler like CFQ?
> If the device does not need cache flushes it should not report requiring
> flushes, in which case nobarrier will be a noop.
OK - that would also mean that mounting with nobarrier should not make a 
performance difference.

> Or to phrase it
> differently:  If nobarrier makes a difference skipping it is not safe.
I do not fully understand that sentence, what do you mean by "makes a 
difference" and "skipping is not safe"?

-Georg