[Techtalk] wdfs vs sshfs vs the perfect fs

Wim De Smet kromagg at gmail.com
Thu Dec 4 10:41:08 UTC 2008


Hi,

On Wed, Nov 26, 2008 at 2:26 AM, Kelly Jones
<kelly.terry.jones at gmail.com> wrote:
> I recently installed wdfs and sshfs on my FreeBSD server + mounted a
> filesystem under each.
>
> "df -k" and "tail -r" work great under sshfs.
>
> "df -k" doesn't work under wdfs (always shows 100% usage) and "tail
> -r" just hangs.
>
> sshfs also seems a little faster. Is all this normal?
>
> I figured webdav would handle "tail -r" better using HTTP's "Range"
> parameter, but I guess not. How does sshfs get to the end of a file so
> fast w/o doing a sequential read?

I reckon wdfs isn't the best possible implementation (alpha quality
maybe?). sftp is a pretty well defined protocol with support for among
other things file attributes and reading/writing from a certain byte
offset, just like you would on a local filesystem. [1]

> What's the best way to mount a remote disk assuming I don't have root
> access on the target server? sshfs? wdfs? something else?

You'll probably be mounting the filesystem through some fuse module
either way. If wdfs is as limited as you say, I'd go for sshfs. I'm
assuming sshfs is by now pretty stable and robust. Keep in mind
there's some overhead involved with encrypting all traffic. It'll be
about half the speed of your connection to the host. Or something, I
just made that figure up. (depends on cpu speed, algorithm etc)

> Specially interested in "random access" files like DBMs or
> MySQL/PostgreSQL files.

I wouldn't really try running a dbms with a remote filesystem store.
Usually it says something in the manual about not ever trying that,
with big warning signs around it. But then if the data isn't too
critical it could work. There's a problem here with reliability
though, what happens when your network connection goes down? Will the
data be in a consistent state? You would almost certainly be restoring
from backup whenever that happens.

Personally I think it's a good place to store the backups, not so good
to run the database off. YMMV.

regards,
Wim

[1]: http://tools.ietf.org/html/draft-ietf-secsh-filexfer-13#section-8.2.1


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