On Thu, 4 May 2017 09:55:51 +0200 Andreas Klauer <Andreas.Klauer@xxxxxxxxxxxxxx> wrote: > For example? I was under the impression that pretty much all of them do. > Even the ones that don't advertize it returned zero after trim for me. > [Sometimes you get original data but that's Linux; gone after drop_caches] > (Of course, I don't have access to that many different models of SSD...) > > But what do they actually return then? Original data? Consult Wikipedia at least, if not the original ATA standards documents: https://en.wikipedia.org/wiki/Trim_(computing)#ATA Can return "undefined", "something that is the same every time" or "zeroes". Apparently the OS can query which is to be expected with a particular device, but firstly, you can't necessarily trust that 100%, and secondly, that's operating on a level lower (ATA) than where md is. -- With respect, Roman -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
