Sid Boyce wrote:
The last kernel problems I had going back a few months was with XFS where modules were being zeroed out on boot sometimes, so I moved to ext4.
ext4 is has options like 'write-through', that disallow buffering of large writes. If you have unreliable hardware, subject to crashes, it is probably a better choice. xfs was designed for servers that have UPS's -- if used with RAID, then with battery back-up on the RAID card as well, it wasn't designed for systems that could crash at any point.... You have to match the file system with your system's usage/reliability. My systems are all on UPS's, I think I had one XFS file corruption in the 10+ years I've been using it...but my systems are also usually on 24/7. On my largest array (a home server), I get max-read/write (large files) of 1GB/s read & write. What do you get with ext4? The file zeroing, BTW, was required for SGI's "Trusted Irix", as any object in the system must be zeroed out before being given to a user. Since XFS allows you to allocate space and THEN write to it -- if you allocate the space and you think you've written to it, but the kernel hasn't flushed it's buffers yet...(between xfs's delayed writes and kernel's buffering can be over 15 seconds or more (it is tunable...BTW to more often or less ... on a laptop setting it to 60 seconds can let the hard disk stay off for most of the time).... BUT....file 'meta' info (names creation, size) gets written immediately to the log...it's file 'data' that can be slower to flush (again, a tunable in /proc), but if you crash or lose power before your buffers are flushed, then the allocated space is ensured to be zeroed when the fs is mounted -- otherwise, you run into a security risk of being able to read someone else's data. It USED to be allowed to disable 'unwritten extent support' at mkfs time, but apparently it was considered too insecure. -- To unsubscribe, e-mail: opensuse-factory+unsubscribe@opensuse.org For additional commands, e-mail: opensuse-factory+help@opensuse.org