Is the -chunks option lenient or not?

[Christoph]

@TheBestPessimist

You can also verify the integrity of snapshots with the -chunks option. Unlike the -files option, this option will download and check each chunk once. The list of verified chunks will be saved to .duplicacy/cache/storage/verified_chunks and chunks in this file will not be verified again in subsequent runs. You can delete this file to force the check command to verify all chunks

So if I use the -chunks option, does that increase or decrease my chances of discovering problems in the storage? On the one hand, it says that it will download and check each chunk (which increases chances of discovering problems) but on the other hand it also says that it will do so exactly once (and I take it that it will assume everything is fine forever after), which decreases chances of discovering problems, right?

Edit: Just noticed another complication of this matter:

2022-06-14 22:20:14.900 DEBUG CHUNK_CACHE Chunk 94a944009abcf044ebe109234fa8d857dac805d93723411bef24f3dbbdd7de17 has been loaded from the snapshot cache
2022-06-14 22:20:14.901 DEBUG CHUNK_CACHE Chunk d0895b205b4b46f3f0ff8725ec9045d728b06067f588de45bf36ab22cdb6ed28 has been loaded from the snapshot cache
2022-06-14 22:20:14.907 DEBUG CHUNK_CACHE Chunk 3b5eb55f8439d829a66bac10e4275da3733c61cdd53c07e9050dc7dc2d42c73c has been loaded from the snapshot cache
2022-06-14 22:20:14.916 DEBUG CHUNK_CACHE Chunk dcf7d579d1fab734f4b479de2cfed40637a1e08de87f1cf74d72f332a916cfb7 has been loaded from the snapshot cache
2022-06-14 22:20:14.922 DEBUG CHUNK_CACHE Chunk 2f95ea07685a42761f902551c5bd802c27a38ec8025aa10dbedfb2b52d46602f has been loaded from the snapshot cache
2022-06-14 22:20:14.933 DEBUG CHUNK_CACHE Chunk 2dbd6a998a37370ed1f66c7e25d746cf250fb343205777bf494bf196fd726ee9 has been loaded from the snapshot cache
2022-06-14 22:20:14.941 DEBUG CHUNK_CACHE Chunk a4490d63bf7ef49febea25f84c6707fced467a4d9baf918af23f52322f48cbfe has been loaded from the snapshot cache
2022-06-14 22:20:14.943 DEBUG CHUNK_CACHE Chunk 9da1e38dc1a4d5b323820af463a0a9b8d7c2b5e240d04e9fba48013a400c66a2 has been loaded from the snapshot cache

Note the “has been loaded from the snapshot cache”. My understanding is that this means that the chunks are not necessarily downloaded from the storage (as it says in the documentation) but taken from the local cache, if available. And I guess that means, that this further decreases chances of discovering problems in the storage, because at least some of the chunks being verified are not actually the chunks from the storage, right?

[saspus]

@Christoph

does that increase or decrease my chances of discovering problems in the storage?

Yes, in the sense that it confirms that “you can get your file back at least once”.

I agree, this is of questionable usefulness: as if you don’t trust your storage remote – checking just one time that they got the file, does not mean that they will keep your file in the future.

@Christoph

My understanding is that this means that the chunks are not necessarily downloaded from the storage (as it says in the documentation) but taken from the local cache, if available.

Yes. The app checks if the file is on the storage first, if so - it checks if the file is in the local cache, and takes it from there. If the file is not present in the storage – it won’t bother checking for it in the cache, as far as I remember.

@Christoph

And I guess that means, that this further decreases chances of discovering problems in the storage, because at least some of the chunks being verified are not actually the chunks from the storage, right?

I don’t think it matters, because each chunk will get checked exactly once anyway: either with -check, or, if it happens to be in the cache it must have been needed and successfully used – meaning it’ OK.

I still feel that checking of file integrity on the cloud provider, even once, is a waste of time. I pay provider to keep an eye on my files – precisely to not to have to worry about this.

Running check without arguments is a useful features perhaps – especially if you use prune – just as a safeguard in case duplicacy deleted something it should not have as a result of some undiscovered bug.

[Christoph]

@saspus

I agree, this is of questionable usefulness: as if you don’t trust your storage remote – checking just one time that they got the file, does not mean that they will keep your file in the future.

Did you not forget to metion something important here?

@saspus

I still feel that checking of file integrity on the cloud provider, even once, is a waste of time. I pay provider to keep an eye on my files – precisely to not to have to worry about this.

Oh, there it is. :

@saspus

I don’t think it matters, because each chunk will get checked exactly once anyway: either with -check, or, if it happens to be in the cache it must have been needed and successfully used – meaning it’ OK.

Oh, so the cache is only an upload cache, i.e. whatever is there, has been downloaded from the storage? Good to know.