XFS: RevServer, web hosts, and you

Andre Garzia andre at andregarzia.com
Tue Jan 22 15:53:29 EST 2013


Hey Folks,

I am pretty happy with EXT3, I would only move to ZFS if it had stable
linux support. My dream system is a FreeBSD server with ZFS and LiveCode
Server but unfortunately we don't have LC Server for FreeBSD and while I
could get the linux version running thru Linux ABI, I could not get RevDB
MySQL adapter working.

Now to move back on topic. I see lots of guys and gals here using shared
accounts and I advise against it. Shared accounts may be cheap but once you
need something more complicated, then you're lost.

The alternative is to pick a VPS where you control everything and this has
a learning curve but it is worth it. For those that want a DIY approach, I
recommend getting a linode (www.linode.com), they are as cheap as 20 USD
per month and they are gorgeous.

Linode is unmanaged, it means that mostly you need to do your own stuff but
their helps and guides are very easy to follow and they provide
pre-assembled images that are easy to use. I could not be happier.

If I need anything, I am just an ssh connection away from installing it and
yes Ubuntu server works quite well for me.

Cheers
andre


On Tue, Jan 22, 2013 at 6:41 PM, Richmond <richmondmathewson at gmail.com>wrote:

> On 01/22/2013 10:32 PM, Phil Davis wrote:
>
>> Great sleuthing, Richard! Thanks for sharing what you learned.
>>
>> Phil
>>
>>
>> On 1/22/13 11:33 AM, Richard Gaskin wrote:
>>
>>> 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<http://twitter.com/FourthWorldSys>
>>>
>>> __
>>>
>>
> Here's my 2 leva worth:
>
> Recently installed an Ubuntu distro on a Pentium IV using Ext4 and had the
> system lock-up irretrievably on me:
>
> being a sucker for punishment, I reinstalled 3 times and got the same
> result every time:
>
> eventually reinstalled using Ext3 and after 3 months have had not a
> whisper of a problem.
>
> So I am steering well clear of Ext4.
>
> [Word of warning: unscientific prejudice]
>
> Richmond.
>
>
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