Md5 Question, is there any reason a md5 hash should change.

[sandamn2036]

I've been doing some testing with Freenas before i put a machine in production and i'm seeing some interesting behavior when running md5 on the files i have loaded on the box. This doesn't seem to be common to a single hardware configuration. in both test systems i am only using a single disk for the storage pool. its all i can spare at the moment.

I loaded a ~200gb file on the system using nfs and rsync -av.
then i ran a md5 on the file twice and this is the result.

Code:

chris@Manjaro ~/D/n/c/dump> md5sum -b IOS.iso
4321491d854ffe7bcd827b7b8f41cc6b *IOS.iso
chris@Manjaro ~/D/n/c/dump> md5sum -b IOS.iso
52f49ef9a28af907c842041e14a42a0a *IOS.iso
chris@Manjaro ~/D/n/c/dump>

I ran this same test on a prior setup with the same resualt.
None of the hash results match the hash i get from running this on the local copy of the file. If i run the hash on the Freenas system i get different hash results with each run.

 

[danb35]

The only reason an md5 hash would change, AFAIK, is that the contents of the file have changed. Disk errors could explain that, though they should be indicated in the pool status.