[gpfsug-discuss] AFM weirdness

[Venkateswara R Puvvada]

I believe this error is result of preallocation failure, but traces are 
needed to confirm this.  AFM caching modes does not support preallocation 
of blocks (ex. using fallocate()). This feature is supported only in AFM 
DR.

~Venkat (vpuvvada at in.ibm.com)



From:   "Simon Thompson (IT Research Support)" <S.J.Thompson at bham.ac.uk>
To:     gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date:   08/23/2017 03:48 PM
Subject:        Re: [gpfsug-discuss] AFM weirdness
Sent by:        gpfsug-discuss-bounces at spectrumscale.org



OK so I checked and if I run directly on the "AFM" FS in a different "non
AFM" directory, it works fine, so its something AFM related ...

Simon

On 23/08/2017, 11:11, "gpfsug-discuss-bounces at spectrumscale.org on behalf
of Simon Thompson (IT Research Support)"
<gpfsug-discuss-bounces at spectrumscale.org on behalf of
S.J.Thompson at bham.ac.uk> wrote:

>We're using an AFM cache from our HPC nodes to access data in another 
GPFS
>cluster, mostly this seems to be working fine, but we've just come across
>an interesting problem with a user using gfortran from the GCC 5.2.0
>toolset.
>
>When linking their code, they get a "no space left on device" error back
>from the linker. If we do this on a node that mounts the file-system
>directly (I.e. Not via AFM cache), then it works fine.
>
>We tried with GCC 4.5 based tools and it works OK, but the difference
>there is that 4.x uses ld and 5x uses ld.gold.
>
>If we strike the ld.gold when using AFM, we see:
>
>stat("program", {st_mode=S_IFREG|0775, st_size=248480, ...}) = 0
>unlink("program")                       = 0
>open("program", O_RDWR|O_CREAT|O_TRUNC|O_CLOEXEC, 0777) = 30
>fstat(30, {st_mode=S_IFREG|0775, st_size=0, ...}) = 0
>fallocate(30, 0, 0, 248480)             = -1 ENOSPC (No space left on
>device)
>
>
>
>Vs when running directly on the file-system:
>stat("program", {st_mode=S_IFREG|0775, st_size=248480, ...}) = 0
>unlink("program")                       = 0
>open("program", O_RDWR|O_CREAT|O_TRUNC|O_CLOEXEC, 0777) = 30
>fstat(30, {st_mode=S_IFREG|0775, st_size=0, ...}) = 0
>fallocate(30, 0, 0, 248480)             = 0
>
>
>
>Anyone seen anything like this before?
>
>... Actually I'm about to go off and see if its a function of AFM, or
>maybe something to do with the FS in use (I.e. Make a local directory on
>the filesystem on the "AFM" FS and see if that works ...)
>
>Thanks
>
>Simon
>
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