On Fri, 2026-05-22 at 09:53 -0600, Charles Curley wrote: > I have four four terabyte hard drives. Each has a partition on it. > The > four partitions comprise a RAID 5 array using mdadm. On top of that, > LUKS encryption, then LVM with ext4 logical volumes.
I remarked to a local computer repair shop that I have a four TB backup drive. He said "replace it. Four TB isn't ready yet." > On one LVM partition I have a number of backup files, tarred, > bzipped, and sha256 and sha512 summed. I have a script which will > find > checksum files, and execute the appropriate program to test the > archives. It puts each program into the background, parallising any > number of checksum tests. > > Starting about a week ago, the script finds an error in one or more > files out of several. Results are inconsistent: one pass may find an > error in a given file, the next pass not find any errors in it. > Running > checksums manually, one at a time, does not turn up an error. Running > "tar tvf" finds no error in a suspect file. Running "bunzip2 -t" also > turns up no error. Only running the script turns up any errors. > > I create two checksum files when I create the backups, for sha256 and > sha512. After this problem surfaced (about a week ago), I then made > two > new checksum files of a suspect file. The two checksum file pairs > (e.g. both sha512sum files) show the same checksums. The script now > tests using both the old and new checksum files. Sometime only one > pair > of checksum files fail the suspect file. > > In addition to all of that, I also get the occasional "bad message" > error. I have no idea what that means, but an fsck seems to deal with > it. > > To be thorough, I have run extended SMART tests on the hard drives, > kicked mdadm into testing the RAID array, and fscked the LVM > partitions > on the RAID array. Only fsck turned up issues, and that has not > stopped. > > I also back some of this up to offsite USB drives. I ran the script > on > one of those, using a different computer. No errors reported. > > I have a hypothesis as to what is going on, but would like to hear > from > you before I discuss it. >
