On 2020-10-31 10:46 p.m., Tim via users wrote:
On Sat, 2020-10-31 at 16:11 +0000, lancelassetter@xxxxxxxxx wrote:
Will NFS tell you data has been corrupted during the transfer and
write process?
Does any filing system? In general, writes to storage are assumed to
have worked unless something throws up an error message. Your hard
drive could be silently corrupting data as it writes to the drive due
to various reasons (defects in its media, bugs in its firmware,
glitches from bad power supplies). You'd never know unless your
filing system did a sanity check after writing. Some specialised ones
might do that, but the average ones don't
You are correct for some very popular filesystems. EXT2/3/4, XFS, NTFS
etc. will not detect this situation. However, newer filesystems (<10
years old) do handle silent data glitches, bad RAM and cosmic ray hits
correctly.
BTRFS has been the default filesystem on SUSE Linux for years, and is
now the default filesystem on Fedora-33. ZFS is an optional filesystem
on Ubuntu-20 and all the Berkeley-derived Unixen like FreeBSD, and
standard on Oracle Linux and Solaris. BTRFS and ZFS are both COW
filesystems using checksumming of both data and metadata. When you push
something to the disk(s) with some kind of RAM error or power glitch,
the first write will be stored with the error, and then the checksummed
metadata is simply redirected to reference the new stuff. This will
detect the checksum errors on the data on ZFS with the reread to verify
the checksum, but I believe that BTRFS will return a successful write
without one of the RAID configurations set on the pool. If you are
running one of the RAID configurations, the checksum error will be
detected before the write completes. To guard against on-disk
corruption (bit rot), both ZFS and BTRFS will also correct it on the
next read of that data if you are running the filesystem in one of the
RAID-z configurations (multiple copies stored), or upon running a
filesystem integrity check.
--
John Mellor
_______________________________________________
users mailing list -- users@xxxxxxxxxxxxxxxxxxxxxxx
To unsubscribe send an email to users-leave@xxxxxxxxxxxxxxxxxxxxxxx
Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/
List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines
List Archives: https://lists.fedoraproject.org/archives/list/users@xxxxxxxxxxxxxxxxxxxxxxx
