Richard,
Thanks for this useful (and strategic in about preventing problems) HOWTO alert.
Pierre
Le 22 janv. 2013 à 20:33, Richard Gaskin a écrit :
> I recently had occasion to learn a bit more about file systems than I had
> intended, and will share what I've learned here because it may affect some
> RevServer or Rev CGI installations on third-party hosts:
>
>
> PROBLEM: Some file I/O operations fail under XFS
> ------------------------------------------------
> Dreamhost and some other web hosting companies have begun rolling out new
> servers which use the XFS file system.
>
> XFS is said to have better performance than EXT3 and even EXT4 used on most
> Linux systems, but apparently this comes with a risk of compatibility issues.
>
> With LiveCode I've found two specific issues, though there may be others:
>
> 1. put url ("file:PathToLocalFile")
> This fails, with sysError reporting 75. Oddly, using
> "open..."/"read..."/"close..." works fine.
>
> 2. put the files
> This also fails, always returning empty even when you know there are files
> there.
>
> While researching this I found some comments in the RealBASIC list archives
> suggesting that the RB engine also has problems with the XFS file system, so
> this is not solely a LiveCode issue.
>
> In fact, it seems there may be a few other programs that have also
> experienced problems with XFS.
>
>
> DIAGNOSIS
> ---------
> You can determine which file system your host is using by logging into the
> system via SSH and running this command:
>
> df -T
>
> This will produce a columnar output which lists the various volumes and their
> file systems available to your account. Note the second column on the line
> for /home (often the last line of the output). It's usually either EXT3,
> EXT4, or XFS.
>
> If it's XFS you may want to try a quick script to verify that your system is
> having the same limitations I had, either attempting to get a list of files
> using "the files" or reading a local file using "put url...".
>
>
>
> REMEDY: Short-term
> ------------------
> If your system is using XFS, the quickest short-term solution is to ask your
> web hosting company to move your account to a system that is both 32-bit
> compatible and also uses either EXT3 or EXT4.
>
> With Dreamhost, it took a little back-and-forth via email, but as with the
> RealBASIC user I'd come across they eventually offered to move my accounts to
> a compatible system.
>
> Hopefully your web host will be able to do the same.
>
>
>
> REMEDY: Long-term
> -----------------
> With the apparent growing popularity of XFS on web servers, clearly any
> long-term solution will require a version of the LiveCode engine which is
> compatible with XFS.
>
> I've been using my Dev Program "Quick Incident" benefits to enlist the
> assistance of David Williams at RunRev, who's been enormously helpful in
> going through the code to try to pinpoint the underlying cause.
>
> His diagnosis is still ongoing at the moment, and as I learn more I'll report
> back.
>
> If we're lucky we'll find that there are alternative API calls that RunRev
> could use for XFS which will take care of this. If so, we can then expect a
> future version of LiveCode to be compatible with XFS.
>
> We may also find that the issue may be a bug in the driver or other component
> in the system, in which case we'll have to monitor progress on that and see
> how it goes.
>
>
> Hopefully one way or another we'll have a good long-term solution in place
> soon.
>
> The RunRev team is putting in an admirable effort toward this, and in the
> meantime if you experience file I/O issues on your web server and can verify
> that your host is using XFS, you may want to contact your hosting company to
> see if they can move your account to a machine using a different file system.
>
> --
> Richard Gaskin
> Fourth World
> LiveCode training and consulting: http://www.fourthworld.com
> Webzine for LiveCode developers: http://www.LiveCodeJournal.com
> Follow me on Twitter: http://twitter.com/FourthWorldSys
>
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--
Pierre Sahores
mobile : 06 03 95 77 70
www.sahores-conseil.com
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