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I would say that most places that are using XFS at scale are doing so with an external RAID array or SAN that handles all of the individual disks and presents a
by mprovost 12y ago
I would say that most places that are using XFS at scale are doing so with an external RAID array or SAN that handles all of the individual disks and presents a single logical LUN to the filesystem. ZFS is fairly unique in that it combines lower level disk and RAID management with a filesystem, typically these functions were handled in separate layers (like md), or in hardware.
Usually I hear people complaining about slow file creates/deletes/renames with ZFS or slowness navigating or dealing with large directories. A quick Google confirms that there are lots of people that have seen these behaviours. But I don't use it myself so I don't have any specific data. I was just trying to say that ZFS has a reputation as being a better filesystem, but not a faster one, at least with the people I talk to about storage.
ARC is a technology from IBM. Intent logs go way back. Sure ZFS is doing some interesting things, but it's a bit ironic to talk about innovation given the fact that it was more or less based on Netapp's WAFL filesystem, and all of the lawsuits that followed on from that.
- ryao 12y agoI believe that the people with whom you spoke are referring to getdents() being slow when the cache is cold. That is because ZFS does not at this time implement directory prefetch logic. That will change in a future release of ZFSOnLinux, but it is a low priority because cold cache performance is not terribly important for production use. I am beginning to think that not only do you not use ZFS, but that you have never used ZFS. I suggest that you try running your own benchmarks and workloads on it. It is a joy to use. I think you would agree if you were to use it in a blind fold comparison test.