[mythtv] Backend process dies at 4GB file limit?

Buzz buzz at oska.com
Thu Jan 19 05:02:29 UTC 2006


This isn't relevant to the original thread/topic, but...
1) backend isn't fulltime linux.
2) I never said I wanted to access myth/video in both OS's, although, that's
not a bad idea.
3) disk/s aren't dedicated to myth, contain significant(hundreds of GB's)
other data required in both OS's and remotely, and impractical to copy
back-and-forth lots between changing OS/s.  Disk/s are used for myth simply
because they are "big". (2x300GB,1x250GB, all FAT32).
4) samba IS used for other systems to access files (when in linux), with
identical sharing setup in windows, so that share/file availability isn't
compromised by changing OS.


There are plently of ways for me to "get around" the problem , but that
doesn't mean it's not a problem when the backend crashes.  :-)    

(I mean, disk is cheap, I've already relocated my /myth folder to another
non-fat32 disk since then, and will be moving it back onto fat32 again, so
Isaac can have his backtrace.... hopefully.)

Buzz.

> -----Original Message-----
> From: mythtv-dev-bounces at mythtv.org 
> [mailto:mythtv-dev-bounces at mythtv.org] On Behalf Of Lincoln Dale
> Sent: Thursday, 19 January 2006 2:39 PM
> To: 'Development of mythtv'
> Subject: Re: [mythtv] Backend process dies at 4GB file limit?
> 
> I don't get it.
> 
> you're implying that you have a backend which isn't full-time 
> linux but also runs windows.
> when you boot into windows, you want to be able to watch the 
> video streams - but presumably as raw files as the backend 
> isn't up, ergo you can't watch them via mythfrontend.
> 
> in which case, why not use a real filesystem 
> (ext2/3/whatever) as your recording partition and _copy_ the 
> videos you want to watch to another partition before rebooting?
> 
> or: if the backend (linux) runs all the time, just run samba on it.
> 
> 
> cheers,
> 
> lincoln.
> 
> 
> > -----Original Message-----
> > From: mythtv-dev-bounces at mythtv.org 
> > [mailto:mythtv-dev-bounces at mythtv.org]
> > On Behalf Of Buzz
> > Sent: Thursday, 19 January 2006 3:08 PM
> > To: 'Development of mythtv'
> > Subject: Re: [mythtv] Backend process dies at 4GB file limit?
> > 
> > Wouldn't it be reasonable if it barfed the recording 
> > partially/entirely WITHOUT crashing mythbackend, rather 
> than crashing 
> > entirely as it does now.
> > 
> > Isn't that theoretically easier to fix?
> > 
> > 
> > Pseudo-code that could be plugged in somewhere:
> > 
> > ------------------------------
> > //  4GB = 4294967296Bytes = 1024x1024x1024x4 . Abort 4kB 
> short of that 
> > for the buffers to flush?: 4294963200 = 4GB-4kB If ( 
> [filesystem type] 
> > == 'fat32' && [recording size] > 4294963200 ) {
> > 	['abort' recording nicely here];
> > }
> > ------------------------------
> > 
> > 
> > Buzz.
> > 
> > > -----Original Message-----
> > > From: mythtv-dev-bounces at mythtv.org
> > > [mailto:mythtv-dev-bounces at mythtv.org] On Behalf Of Joe Votour
> > > Sent: Thursday, 19 January 2006 1:42 PM
> > > To: Development of mythtv
> > > Subject: Re: [mythtv] Backend process dies at 4GB file limit?
> > >
> > >
> > >
> > > --- Buzz <buzz at oska.com> wrote:
> > >
> > > > Are you interested in this scenario:
> > > >
> > > > Backend saves files to FAT32 partition.
> > > > Backend tries to exceed 4GB (or there abouts) while unattended.
> > > > Backend dies with error "File size limit exceeded"
> > > > emitted by OS.
> > > >
> > > >
> > > > Backend's last message prior to dying was:
> > > > "TFW: safe_swite() funky usleep"
> > > > (message comes from ThreadedFileWriter.cpp )
> > > >
> > > >
> > > > Buzz.
> > > >
> > > > P.S. Before you tell me "FAT32 is a bad, naughty, unsupported 
> > > > filesystem"..
> > > > tell me another filesystem that works under both MS Windows
> > > and linux,
> > > > reliably, and I'll happily change (I'm waiting in 
> anticipation of 
> > > > native
> > > > ext2/3 windows drivers or NTFS write support in the 
> kernel - it's 
> > > > a long
> > > > wait)
> > > >
> > >
> > > <snip>
> > >
> > > Unfortunately, there's nothing that the backend can 
> really do in the 
> > > current implementation.  The 4GB limitation is in the
> > > FAT32 filesystem itself (according to Microsoft's documentation).
> > >
> > > About all the backend could do is try to split the file 
> up, but that 
> > > adds a lot of overhead and bookkeeping.  However, seeing as there 
> > > are many Linux native filesystems that support files larger than 
> > > 4GB, I doubt that the developers would be interested in trying to 
> > > fix this.
> > >
> > > I won't tell you that FAT32 is unsupported (because that's not 
> > > true), but it is bad and naughty.  :) There are a few
> > > ext2 drivers available for Windows, some free, some commercial.
> > >
> > > -- Joe
> > >
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