The Evolution of Stupidity: File Systems

http://www.enterprisestorageforum.com/storage-management/the-evolution-of-stupidity-file-systems.html

by darkduck • 15 years ago

44 25 15 years ago

wccrawford• 15 years ago

I'd hardly call people who design file systems stupid.

I don't expect them to be psychic, or know everything. I don't even expect them to be the most knowledgeable person in their field. They're just human.

Calling them stupid because you saw something they didn't isn't just rude, it's ridiculous.

0x123• 15 years ago

I'm fine with some of the criticisms but using XFS as the posterchild example of a free file system done 'right' is a bit much. XFS has absolutely terrible performance for lots of use cases (deletions, for instance).

What the author also fails to understand - apparently - is that the problems plaguing the storage industry are perennial, they will never be resolved. We will always yearn for more storage that is more reliable at a lower price-point, no matter how good our current technology is.

dexen• 15 years ago

> XFS has absolutely terrible performance for lots of use cases (deletions, for instance).

Depends /heavily/ on hardware. XFS evolved on high-end machines, and performs awesomely when you have:

* EITHER large write cache (write cache size >> journal size), think `decent RAID controller',

* OR at least put the journal is on a separate harddrive -- which is very real on average workstation.

Been there, done that, the difference is astonishing.

It boils down to specific media access patterns: XFS uses mixed physical/logical journaling; some operations cause a lot of `physical' (i.e., low-level) representation of directory and file metadata to be written to the journal.

Having harddrive's heads fly back-and-forth between different areas (journal vs. metadata) is a sure recipe for abysmal performance. On the other hand, if you have large write cache to handle journal, or at least employ separate harddrive head to serve journal, directory and file metadata has pretty good locality (thanks to very smart allocator) and the other head doesn't have to move too much.

EDIT:

it's worth noting XFS handles large (multi-gigabyte) files very well, as compared to other filesystems. Both r/w access and creation/removal is fast, on any hardware. This is XFS's original and primary use case: handling large multimedia and scientific datasets.

Want to keep countless virtual machine images? XFS is the way to go, especially thanks to smart allocator which lessens fragmentation as compared to competing filesystems.

tl;dr: XFS is optimized for handling large files. With the right setup -- possible on mid-end hardware -- it also handles numerous small files (say, linux-kernel-size projects) very well.

0x123• 15 years ago

Yes, large files are fine.

But contrary to your claim many (10's or 100's of millions) of small files and performance is terrible, orders of magnitudes slower than vanilla ext3.

I don't consider the linux kernel to be 'many' files.

rbanffy3• 15 years ago

> Having harddrive's heads fly back-and-forth between different areas (journal vs. metadata) is a sure recipe for abysmal performance.

I wonder how XFS performs on SSD, where head transit is not an issue.

spudlyo• 15 years ago

XFS gets some things right. As far as I know it's one of the few Linux filesystems that doesn't serialize writes to O_DIRECT opened files, which is why it's very popular for databases.

Florin_Andrei• 15 years ago

> XFS has absolutely terrible performance for lots of use cases (deletions, for instance).

And has outstanding performance for lots of other use cases (handling large files, for instance).

Just like any other FS out there.

mother• 15 years ago

It's not a very good article. It's rambling, almost incoherent.

epo• 15 years ago

A linkbait headline that makes the writer seem like the one that is stupid.

If anything he seems to be saying that old known mistakes don't get fixed as we don't learn from the past. This is not evolution but it is an example of the widescale misunderstanding of that word that seems to be common in some parts of the world, it is in fact the exact opposite.

perlgeek• 15 years ago

The article talks about repeating mistakes, and descends into the world of file systems, but I didn't quite understand what the problem is that is repeated there.

Anybody care to explain?

(FWIW my impression is that there's lots of reinventing going on in the open source FS development; everybody wants to reinvent the cool features from ZFS, but with improved performance or a slightly different architecture, and they all seem to be eager to learn from their own and other people's mistakes).

rbanffy3• 15 years ago

> everybody wants to reinvent the cool features from ZFS,

Perhaps because ZFS cannot be integrated into Linux due to licensing issues. If Oracle would be generous enough to offer it under a compatible license, I have little doubt it would be very welcome, despite some of its architectural incompatibilities.

naner• 15 years ago

If Oracle would be generous enough to offer it under a compatible license, I have little doubt it would be very welcome, despite some of its architectural incompatibilities.

Oracle is developing Btrfs for Linux, I'm not sure they have any desire to make ZFS more attractive to Linux users.

Also, didn't Apple roll out ZFS on OSX and then abandon it? Does anyone know the reasoning behind that? Perhaps ZFS was over-hyped or is only useful in certain scenarios.

scott_s• 15 years ago

I had the same question. He has no clear thesis. He never says, "The problem with current filesystems is: ___".

mmatants• 15 years ago

I, for one, thought that he was going to argue against the overall hierarchical FS metaphor. Personally, I wonder what things would be like if the OS provided a key-value store (or some such NoSQL-ish API) as a core service instead.

srdev• 15 years ago

I suspect that you would still have some semblance of built over such a file-system. Hierarchy is useful for organizing data, and I often find myself using keys that allow me to abstract hierarchy in my NoSQL systems. ex: "/foo/bar/0113" -> data

ori_b2• 15 years ago

is a hierarchy all that different from a key value store?

shawndumas• 15 years ago

print version: http://www.enterprisestorageforum.com/print/storage-manageme...

ori_b2• 15 years ago

Did he have a point?

radicalbyte• 15 years ago

Young people only want to talk about the "presentation"? Appliance based systems were far easier to "management" than provisioning file systems?

Rambling & incoherent this article is.

thirdstation• 15 years ago

I think he is confusing ignorance for stupidity. It's difficult to find good, sensible information about file systems. And I'm only talking about selection for using a file system. If I wanted to develop one, where would I go to learn?

noahdesu• 15 years ago

I think this article is (doing a bad job of) attempting to explain that limitations behind the current byte-stream oriented interfaces and hierarchical organizations that have been around for 20 years. These two limitations show their heads when 1) people want extreme speed (parallel I/O), and 2) file systems begin to contain billions of files. People are storing more and more structured data, and building enormous middleware layers on top of the read/write to only present richer interfaces to higher levels.

The Evolution of Stupidity: File Systems

Related Stories