CODEWITHSUNDEEP
filesystemsntfscorruption
joe-jeff
joe-jeff

Reputation: 336

File System with "Corruption" protection

I am developing a system which copies and writes files on NTFS inside a virtual machine. At any time the VM can poweroff (direct shutdown). The poweroff is controlled from the outside so I do not have any way to detect it. Due to that files and complete directories which are being written to get lost. Is there any way to prevent that or do I have to develop my own file system? I have to store the files on the local disk and cannot send files via network.

Upvotes: 0

Views: 90

Answers (2)

Mike Marynowski
Mike Marynowski

Reputation: 3439

If you write data to a file opened with "write through" enabled, the method only returns after the data is physically written to the disk so you can be sure it got written. You normally do that by passing in a WRITE_THROUGH flag when you open the file.

Upvotes: 0

Eugene Mayevski 'Callback
Eugene Mayevski 'Callback

Reputation: 46070

There always exists a [short] period between when your data is written (sent to the API) and when this data is written to the physical hardware. If the system crashes in the middle, the data will be lost.

There is a setting in Windows to disable system write cache for certain disks. This setting can help you ensure that the data is at least sent to the host's hardware. Probably that's the answer you've been looking for.

Writing your own filesystem won't help much because it's mainly the write cache that causes the data to be lost. There can exist a filesystem-level cache as well, though, and I don't know if the write cache setting I mentioned above also affects internal filesystem cache.

Upvotes: 1

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