On Sat, Mar 30, 2019 at 09:24:37PM +0800, Qu Wenruo wrote: > > > On 2019/3/30 下午9:14, Supercilious Dude wrote: > > On Sat, 30 Mar 2019 at 13:09, Qu Wenruo <quwenruo.btrfs@xxxxxxx> wrote: > >> > >> If controller is doing so, it must have its own power or at least finish > >> flush when controller writes to its fast cache. > >> > > > > The controller has its own battery backup to power the DRAM cache, as > > well as flash storage to dump it onto in the exceedingly unlikely > > event that the battery gets depleted. > > > >> For cache case, if we have enough data, we could still find some clue on > >> the flush execution time. > >> > >> Despite that, for that enterprise level usage, it's OK. > >> > >> But for consumer level storage, I'm not sure, especially for HDDs, and > >> maybe NVMe devices. > >> > > > > How do you distinguish who is a who? Am I an enterprise or a consumer? > > Easy, price. :P > > To be honest, I don't really care about that fancy use case. > It's the vendor doing its work, and if something wrong happened, > customer will yell at them. > > I'm more interesting in the consumer level situation. The feature seems to be advertised as "power loss protection" or "enhanced power loss data protection". Which makes it sound like a data safety feature when really it's a performance feature. E.g. these are the Intel drives with "EPLDP": https://ark.intel.com/content/www/us/en/ark/search/featurefilter.html?productType=35125&0_EPLDP=True Last I checked there were some that weren't too expensive. --b.
