Messages in this thread | | | From | Ricardo Correia <> | Subject | Re: How to flush the disk write cache from userspace | Date | Thu, 18 Jan 2007 01:15:54 +0000 |
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On Tuesday 16 January 2007 00:38, you wrote: > As always with these things, the devil is in the details. It requires > the device to support a ->prepare_flush() queue hook, and not all > devices do that. It will work for IDE/SATA/SCSI, though. In some devices > you don't want/need to do a real disk flush, it depends on the write > cache settings, battery backing, etc.
Is there any chance that someone could implement this (I don't have the skills, unfortunately)? Maybe add a new ioctl() to block devices, so that it doesn't break any existing code?
I believe it's a very useful (and relatively simple) feature that increases data integrity and reliability for applications that need this functionality.
I think it must be considered that most people have disk write caches enabled and are using IDE, SATA or SCSI disks.
I also think there's no point in disabling disks' write caches, since it slows writes and decreases disks' lifetime, and because there's a better solution.
Personally, I'm not really interested in specific filesystem behaviour, since my application uses block devices directly (it's a filesystem itself). Although I think all filesystems should guarantee data integrity in the face of fsync() or metadata modifications, even if it costs a little performance.
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