New nightly changes


Having seen quite so many errors writing to the disk on Slice I decided to dig in a little deeper and see what’s going on. It turns out that the filesystem was only getting flushed back to the disk when it was unmounted. This means that the only time that the disk was not going to lose data is when you completely shut down properly and pull the power.

I’ve been in communication with the writer of the exfat-fuse driver that we use and he suggested a patch to improve flushing of data to the disk. Basically what this means is that for a small amount of performance loss (only for disk writing not for reading) we have a massively improved reliability to accidentally powering off the slice (power loss, random bugs or just accidentally turning off the wrong switch!)

I’ve checked this into Nightly but think it should go very soon to Stable because it should be a significant improvement in reliability!




that really does explain some of the weirdness, and if a bug causes the HDD to get confused after a spin-down then file system updates would indeed be lost.

can you confirm if it is the file system structure (directories etc) or the file system structure AND data files which may have been added / updated which fail to be written in the scenario you describe…

Also, can you confirm that the patch is not required for NTFS as that already does more frequent writes to the HDD.



No the problem is not caused by spinning down the disk, the problem is caused by powering off (or crashing / rebooting) slice without properly hitting the power -> Power Off System

It also requires that you’ve written something to the disk from Slice i.e. over samba or something… Which is why some people didn’t see it at all, plus quite often you wouldn’t notice at all until the allocations got randomly written over sometime later or you plug into a Windows machine and it would ‘fix’ the drive

No this doesn’t effect NTFS



thanks for the clarification and I now understand why I saw funny things when using samba as well.



BTW, this kind of problem is not new, Microsoft introduced disk caching in the days of DOS and Windows 2/3. This allowed read and write caching to speed up very slow disks. Sadly, the default setting during the beta of a new version of DOS set write cache on for all disks, hard or floppy, so a user could remove a floppy disk and not have the data just written. The default for removable disks was changed later. Similar thing happened later in Windows, when hibernating a USB connected hard disk, the write cache was not flushed as part of the process. OK unless you removed the drive prior to turning on the computer, in which case data / directory structures could be messed up!



Hi Gordon

Would this explain my issue? Where my files weren’t visible and now they seem to have been purged?



Yes I think that when you unplugged Slice it had either crashed or not been shut down and when you plug it into the Windows PC it cleans up which actually means the files get lost.

This shouldn’t now happen