3 ms·

Fair enough, was interrupted while reading on mobile so seems I skipped a section accidentally. Still, this happens quite a bit, in my personal experience and

Fair enough, was interrupted while reading on mobile so seems I skipped a section accidentally. Still, this happens quite a bit, in my personal experience and from what I've read on the mailing lists etc, so shouldn't be downplayed. I've replaced at least 7-8 cables after ZFS started complaining (could be reseating would help but I have enough cables). That's a lot of potential errors other filesystems which don't do error detection on read wouldn't discover, given that I almost certainly wouldn't have found out until much later in that case. I've also read plenty of people who've had ZFS reporting errors which went away after replacing a SAS/SATA backplane.

Modified3019 3y ago
Cables/bad connections are the number one source of errors reported in my experience, and encountering these is to be expected when hooking enough things up for a project. These are _usually_ found in the "Read" or "Write" columns, meaning the hardware involved caught the errors when the data over whatever serial protocol failed it's checksum (CRC32 for SATA I believe), the transmission was then resent and the error reported to the OS/ZFS. These errors only show up for a specific disk. Reseating the connections, making sure there are no harsh bends, and finally replacing the cable is the fix. Rarely, reported checksum errors are stopped because of replacing a cable. I don't have the depth of technical knowledge to understand why this happens. Then you have Controllers/HBA's/Backplanes either going bad, or more often overheating. Put a fan on your HBA. These errors can show up across multiple disks Bad/weak/noisy power supplies, and system overclocking that effects the PCIe bus and attached (like messing with BCLK) can cause havoc as well. Sometimes a CPU/system might have an undocumented bug specific to that system that can cause sanity loss trying to figure out WTF is going on. I've also noticed (and have come across a few others as well) that if you have enough Samsung SATA 860 EVOs, a particular one may end up persistently generating just a few errors every so often. I don't recall if these were read/write errors or a checksum error, but a clear and scrub will resolve these without incident. Out of 30+ personal HDDs, I've only ever had one that had started generating checksum errors because it was going to shit. Not counting the laptop HDD that started clicking 20 years ago and taught me a very important early lesson on backups.

Modified3019 3y ago

Cables/bad connections are the number one source of errors reported in my experience, and encountering these is to be expected when hooking enough things up for a project. These are _usually_ found in the "Read" or "Write" columns, meaning the hardware involved caught the errors when the data over whatever serial protocol failed it's checksum (CRC32 for SATA I believe), the transmission was then resent and the error reported to the OS/ZFS. These errors only show up for a specific disk. Reseating the connections, making sure there are no harsh bends, and finally replacing the cable is the fix. Rarely, reported checksum errors are stopped because of replacing a cable. I don't have the depth of technical knowledge to understand why this happens. Then you have Controllers/HBA's/Backplanes either going bad, or more often overheating. Put a fan on your HBA. These errors can show up across multiple disks Bad/weak/noisy power supplies, and system overclocking that effects the PCIe bus and attached (like messing with BCLK) can cause havoc as well. Sometimes a CPU/system might have an undocumented bug specific to that system that can cause sanity loss trying to figure out WTF is going on. I've also noticed (and have come across a few others as well) that if you have enough Samsung SATA 860 EVOs, a particular one may end up persistently generating just a few errors every so often. I don't recall if these were read/write errors or a checksum error, but a clear and scrub will resolve these without incident. Out of 30+ personal HDDs, I've only ever had one that had started generating checksum errors because it was going to shit. Not counting the laptop HDD that started clicking 20 years ago and taught me a very important early lesson on backups.