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Comment by cbsmith | Hacker News Reader

> The comments about btrfs are about 5 years out of date.

Not really. I've tried it, and it still has pain points I'd not like to have in my filesystem. It's like ZFS almost a decade ago (and I'm not talking about features)... although ZFS on Linux vs. btrfs on Linux... right now I'd still go with btrfs.

> Neither of those things were ever true (or are going to be true in the future) for the various ZFS-on-Linux projects (yes, there are multiple.)

I believe there is a shift with regard to this, as demonstrated by the Gentoo project's integration of ZFS.

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> Not really. I've tried it, and it still has pain points I'd not like to have in my filesystem. It's like ZFS almost a decade ago (and I'm not talking about features)... although ZFS on Linux vs. btrfs on Linux... right now I'd still go with btrfs.

Care to elaborate? I've never tried ZFS, but been very happy with btrfs for my smalltime personal usage, I'm wondering why people find it so painful in comparison.

Well, there's just the general lack luster performance: http://www.phoronix.com/scan.php?page=article&item=linux_311...

I've also seen particularly bad pain points when doing things like using it with an NFS server.

ZFS also has "general lackluster performance" in areas like using memory (it requires tons of it). It's inherent in the design of a copy-on-write filesystem.

According to Ted Dunangst: "ZFS wants a lot of memory. A lot lot lot of memory. So much memory, the kernel address space has trouble wrapping its arms around ZFS. I haven't studied it extensively, but the hack of pushing some of the cache off into higher memory and accessing it through a small window may even work." See http://www.tedunangst.com/flak/post/ZFS-on-OpenBSD

Different filesystems are good for different things. If you want a filesystem that has subvolumes, copy-on-write snapshots, built-in RAID, transactions, space-efficient packing of small files, batch deduplication, checksums on data and metadata, and so forth, you have to pay a price. Just the same way as running Apache with all the bells and whistles is not going to be as fast as ngnix.

> ZFS also has "general lackluster performance" in areas like using memory (it requires tons of it). It's inherent in the design of a copy-on-write filesystem.

Those benchmarks aren't about CPU or memory consumption. These days a good filesystem probably should trade memory and CPU for increased performance. Those benchmarks are about throughput/latency.

> Just the same way as running Apache with all the bells and whistles is not going to be as fast as ngnix.

...except ZFS generally performs very well as compared to other filesystems. When it first came out it had all kinds of ugly corner cases where it performed poorly, but it seems to do great these days.

I originally had a lot of text here, but let's just leave it at this... something being in Gentoo doesn't mean it's in any way mainstream. I mean that in the nicest possible way (Gentoo can be fun).

Sorry if you got the idea that I was asserting Gentoo == mainstream. I was merely suggesting that maybe it might be heading towards mainstreaming, and pointing to the Gentoo integration as a step that might make that easier.

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