On 01/04/19 00:45, J. Bruce Fields wrote: > 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. Afaik quite a few consumer Crucial SSDs do have power loss protection (those that advertise it either have a large bank of capacitors on their PCB or use newer flash that for some reason can do without that) -Alberto
