Is ZFS a meme? Does this shit work? I'm considering using this, instead of ext4 with journaled data (100% write penalty).
I benchmarked it vs raid10,far 2, with two disks, and it's okay I guess. raid10,far2 gives Nx read speed, for 2 drives, 2x read speed, with 1x write. ZFS is only giving about 1x read in mirrored mode. Maybe with 100 threads hitting it the total throughput would increase some. I can deal with the reduced read speed, in exchange for all the data consistency checks, but this means nothing if the system is going to crash at any moment, or the next time a new ZFS update comes out or the next time a new kernel update comes out.
Is this reliable enough for production? Is bit rot paranoia overblown? I think journaled data ext4 should take care of problems if the system crashes or the power goes out with no ups, but it does nothing for bit rot, neither does raid unless your using a mode with parity disks.
Yes Yes On Solaris and Fr*eBSD yes, no idea what it is like on Linux. Depends on how important your data is and what scenarios you're comparing
Zachary Hall
If you don't want to waste 8 gibibytes + 1 gibibyte of ram per terabyte of disk just use BTRFS.
Connor Williams
Are you actually using those shitty terms? Computer science is binary, hence it doesn't use base-10 modifiers.
Ian Jones
i've looked at btrfs but that looks even less stable. these are going to be storing vm images, nothing particularly critical but they will take days of time to regenerate if one of those files get corrupted. What I'm thinking of doing now is not having a file system on this at all, just use lvm across the partition, and pump the lvm volumes straight through to the vm's, which will then use ext4 with journaling. I don't see the point of using ext4 with no data journaling, to store vm image files, which then will use data journaling, seems like the cache would fuck this all up on power failure anyway, and ext4 times two both with data journaling, on the partition that stores the image files and inside of the vm, would cut the write performance down to 1/4, which seems stupid.
Aaron Gonzalez
yes
/thread
Matthew Brooks
A good meme, like thinkpads and gnu / linux.
Adrian Bell
but disk storage is done in decimal. It would have been confusing to mix both of them.
I've been running it on my laptop since last January and haven't run into problems with it. I've even run out of power multiple times (when writing files) and it still worked fine afterwords. Do note that the raid 5 and raid 6 are marked as unstable.
Dylan Price
it's part of the kernel that actually looks like a better option, maybe for using inside of the vm's?
what's killing me with this rabbit hole that i've dived into is the multiple layers of caching going on at these levels.
if the guest is using either ext4 with data journaling or btrfs or zfs or something that ensure data is actually written, what happens when any one of these levels lies about when data is actually written, when it is infact only written to cache? i've come to the conclusion that this is all paranoia at this point and to stop digging this hole.
the question then is, is there any point to having a file system with consistency checks hosting VM images with their own file system, or should i just pass an lvm partition through and do it in the vm, or both?
Luke Cooper
Yes it's reliable. If it fits your benchmarks and supports your use-cases, use it. You should have complete and comprehensive backups anyway, so a catastrophic crash should in a worst case lose you an hour or two of data. BTRFS is less stable, but far more promising, and has a lot more active development, especially on Linux. I've been running BTRFS for a few years and have only run into a few issues (my filesystem became corrupted once when it maxed out about 3 or 4 years ago. I could still pull my files off, but I had to rebuild the filesystem. I had my snapshot-based backups become corrupted when my power went out during a backup a year ago, and had to manually fix the snapshots. Other than that, it's been rock solid).
Regardless of what your filesystem is, your system is only as reliable as your backups. Running without backups is begging for catastrophy.
