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Comment by chucky_z | Hacker News Reader

.... XFS?

I've had a single issue across many EBS drives partitioned with only XFS, in several mdadm configurations. The data-loss occured during a maintenance window, so I'm convinced it was an EBS issue and not XFS.

I've also used it on physical hardware and never experienced dataloss, even losing drives in RAID configurations (I will admit I was lucky enough to never lose 2 drives in my normal RAID10 setup).

I've had several filesystems become corrupted, but the XFS community is extremely helpful, and the tooling that comes with it has never failed me in at least letting me figure out what's actually wrong.

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We have some CentOS 7 qemu/kvm servers for hosting dev/test VMs, where the backing VM images are stored to a local RAID array formatted with XFS. Basically a 2-socket server with 128-256GB RAM and an LSI MegaRAID controller with battery-backed, write-back caching. Each virtual disk in a VM is a raw-formatted file in the host filesystem.

We have seen host kernel panics which damage the filesystem such that xfs_repair cannot fix it. It could be mounted read-only, though I am not sure I would trust the content. We just reformatted and rebuilt content from external sources.

What I believe caused this panic was a habit of creating sparse VM disk images. Later, under heavy write loads from multiple VMs, the host OS filesystem seemed to choke under all the out-of-order allocation needed to place new data into those sparse disk images. When we instituted a policy of always preallocating the VM disk files, we never saw this problem repeated.

XFS wasn't able to handle a lot of extents well (which occur with sparse images). The problem was only recently fixed, I think.

That said, it should only cause memory allocation deadlocks, not corruptions.

Ehm, what distro supports xfs out of the box and what are the guides like for setting it up? Also, it seems to be missing features like COW or data checksums (bitrot says hello), and data deduplication seems to still be experimental. Doesn't seem like the next-gen filesystem we should be hoping for.

Redhat and CentOS use XFS by default.

Really not a fan of their package managers.

When you're installing you can select something like "manually set the partitions/disks" and format XFS with basically any distro. It's part of the kernel, and I can't remember installing a distro without that option.

If by that you mean "these distros support XFS, but I don't use them for other reasons (package managers)" . . . OK. Don't use them. But don't criticize a filesystem for unrelated tradeoffs that OSes that support it happen to make.

> Ehm, what distro supports xfs out of the box

Basically all of them.

> what are the guides like for setting it up?

Choose "xfs" instead of "ext4" in the installer.

> Doesn't seem like the next-gen filesystem we should be hoping for.

XFS was an early journaling file system. It wasn't designed to be next-gen, it was designed to be fast, service soft-realtime I/O demands and handle large volumes well.

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