5 ms·
This is true. Which is why we really, really need checksummed filesystems. I am very worried that this hasn't made its way into mainstream computing yet, especi
by jwr 11y ago
This is true. Which is why we really, really need checksummed filesystems. I am very worried that this hasn't made its way into mainstream computing yet, especially given the growing drive sizes and massive CPU speed increases.
- sneak 11y agoFortunately, zfs on Linux is excellent, and is a two-liner on modern Ububtu LTS. (add PPA, install zfs.)
- tshtf 11y agoIs it? I've heard several complains about bugs in FUSE.
- mitchty 11y agoI've a friend that uses it. Can't say it is not buggy, he hit the bug where unlinked files weren't removed. Got to 95% use before finding out he had to reboot/unmount to clean things up. But that means his pool performance is now shit.
- gnoway 11y agoZFS on Linux[0] doesn't use FUSE. [0] http://zfsonlinux.org/ http://zfsonlinux.org/
- tshtf 11y agoThanks, I was unaware. Apparently there is both native ZFS, and FUSE-backed ZFS for Linux: https://en.wikipedia.org/wiki/ZFS#Linux https://en.wikipedia.org/wiki/ZFS#Linux
- barrkel 11y agoI run a 10x3TB ZFS raidz2 array at home. I've seen 18 checksum errors at the device level in the last year - these are corruption from the device that ZFS detected with a checksum, and was able to correct using redundancy. If you're not checksumming at some level in your system, you should be outsourcing your storage to someone else; consumer level hardware with commodity file systems isn't good enough.
- mitchty 11y agoAs a counterpoint I have 6x3TB zfs raidz2 on freebsd at home. I resilver every month and only had one checksum error that turned out to be a cable going bad given it hasn't repeated. Still agree with we need checksumming filesystems though. That and gcc ram to make the data written more trustworthy.
- PhantomGremlin 11y agohad one checksum error that turned out to be a cable going bad given it hasn't repeated I wouldn't assume that it was a cable error. The SATA interface has a CRC check. So the odds are quite high that a single error would simply result in a retransmission. Of course, a plethora of detected SATA CRC errors and resulting retransmissions means that an undetected error could readily slip thru. There should be error logs reporting on the occurrence of retransmission, but I'm not enough of a software person to know how possible / easy it is to get that information from a drive or operating system. OTOH, as you mention later in your post, a single bit error in non-ECC RAM could easily result in a single block having a checksum error. Exactly what you saw!
- wtallis 11y agoHard drives also have spare sectors, so if a defect is detected at one spot in the disk, it will probably never touch that spot again. Simply observing that an error only occurred once does almost nothing to narrow down the possible causes. You have to also be keeping track of all the error reporting facilities (SMART, PCIe AER, ECC RAM, etc.).
- nickpsecurity 11y agoI advocate taking it further with clustered filesystems on inexpensive nodes. Good design of those can solve problems on this side plus system-level. Probably also need inexpensive, commodity knockoffs of things like Stratus and NonStop. Where reliability tops speed, could use high-end embedded stuff like Freescale's to keep the nodes cheap. Some of them support lock-step, too.