Started by BenYeeHua, June 06, 2013, 09:43:33 PM
QuoteHello!This post will be 100% off topic but since your are on a Windows development team I thought I would let you know.We have discovered that the "turn off windows write-cache buffer flushing on the device" option (enabled) causes data loss on reboot when installing Windows updates. We had at least four incidents when our PCs became unbootable since crucial Windows files were wiped out on reboot.I wonder if your team could investigate this issue and release a fix for it.Thank you.[Dangerous setting is dangerous. -Raymond]
QuoteThis extra "flush out your internal RAM buffer too" command is the right thing to do, but it can safely be skipped under very special circumstances: Consider a hard drive with a power supply separate from the computer which can keep the drive running long enough to flush out its internal RAM, even in the event of a sudden total loss of external power. For example, it might be an external drive with a separate power supply that is hooked up to a UPS. If you have this very special type of set-up, then Windows doesn't need to issue the "please flush out your internal RAM buffers too" command, because you have a guarantee that the data will make it to the disk no matter what happens in the future. Even if a transformer box explodes, cutting off all power to your building, that hard drive has enough residual power to get the data from the internal RAM buffer onto the physical medium. Only if your hard drive has that type of set-up is it safe to turn on the Turn off Windows write-cache buffer flushing on the device check box.(Note that a laptop computer battery does not count as a guarantee that the hard drive will have enough residual power to flush its RAM buffer to physical media. You might accidentally eject the battery out of your laptop, or you might let your battery run down completely. In these cases, the hard drive will not have a chance to finish flushing its internal RAM buffer.)
QuoteHaving worked for a company that makes disk drives, I am amused. Steering clear of the dangerous setting doesn't guarantee that you won't get corruption in a power outage. Lots of hard drives cheat and do write caching internally--even when the protocol doesn't allow for it. The drive simply lies to the OS, and says, yeah, those bits are stored. Kill the power too soon, and the lie will be exposed.- Adrian
Quote[Windows tells the drive to flush, and then since it knows that drives lie about flushing, it sends another command saying, "now flush for real, stop pretending". But apparently (according to Adrian above), some drives ignore even this extra bonus flush request, and then you're kind of screwed. -Raymond]
QuoteJoshua and Raymond's comments weren't there when I typed the previous one. Anyway, isn't it possible to make the hard disk device driver delay shutdown for five minutes or so?["Sir, you have to turn off your laptop before we can take off." "Yes, I know. Just four minutes, thirty seconds remaining." -Raymond]
Quote from: edkiefer on June 07, 2013, 10:42:59 AMthere 2 setting under HD .there enable write caching on this device and then sub option of Turn off Windows write-cache buffer flushing .I personally have write caching enabled but not Turn off Windows write-cache buffer flushing .I forget if this was default or I set it .