Hello,
I'm evaluating cephfs on a virtual machines cluster. I'm using
Infernalis (9.2.0) on debian Jessie as client and server.
I'm trying to get some performance numbers on operations like
tar/untar on things like the linux kernel. I have an issue where tar
displays this warning : 'file changed as we read it'. I reproduced the
problem with just the Documentation dir.
root@admin:/mnt/cephfs# rm -rf Documentation ; tar xf
linux-documentation.tar.bz2 ; sync ; tar c Documentation>/dev/null ;
tar: Documentation/parisc: file changed as we read it
tar: Documentation/pcmcia: file changed as we read it
tar: Documentation/phy: file changed as we read it
tar: Documentation/platform: file changed as we read it
tar: Documentation/power: file changed as we read it
tar: Documentation/powerpc: file changed as we read it
tar: Documentation/pps: file changed as we read it
tar: Documentation/prctl: file changed as we read it
tar: Documentation/pti: file changed as we read it
tar: Documentation/ptp: file changed as we read it
tar: Documentation/rapidio: file changed as we read it
tar: Documentation/s390: file changed as we read it
tar: Documentation/scheduler: file changed as we read it
tar: Documentation/scsi: file changed as we read it
tar: Documentation/security: file changed as we read it
tar: Documentation/w1/slaves: file changed as we read it
tar: Documentation/watchdog: file changed as we read it
tar: Documentation/x86: file changed as we read it
tar: Documentation/zh_CN: file changed as we read it
tar: Documentation: file changed as we read it
If I wait between the two commands, the error is reduced but not eliminated:
root@admin:/mnt/cephfs# rm -rf Documenation ; tar xf
linux-documentation.tar.bz2 ; sleep 10 ; tar c Documentation>/dev/null ;
tar: Documentation/virtual: file changed as we read it
tar: Documentation/w1: file changed as we read it
tar: Documentation/watchdog: file changed as we read it
tar: Documentation/x86: file changed as we read it
tar: Documentation/zh_CN: file changed as we read it
tar: Documentation: file changed as we read it
root@admin:/mnt/cephfs# rm -rf Documentation ; tar xf
linux-documentation.tar.bz2 ; sleep 120 ; tar c
Documentation>/dev/null ;
tar: Documentation: file changed as we read it
I'm sure no other client process is not modifying the files. I have
this problem with the fuse client and with the kernel (version in
Jessie) client.
By doing a "stat", I see some meta-data are changed:
root@admin:/mnt/cephfs# rm -rf Documentation ; tar xf
linux-documentation.tar.bz2 ;stat Documentation; tar -c
Documentation>/dev/null ; stat Documentation
File: ‘Documentation’
Size: 14740322 Blocks: 1 IO Block: 4096 directory
Device: 23h/35d Inode: 1099511913288 Links: 1
Access: (0770/drwxrwx---) Uid: ( 1000/ XXXX) Gid: ( 1000/ XXXX)
Access: 2016-01-15 16:51:40.882143334 +0000
Modify: 2015-05-12 09:34:49.000000000 +0100
Change: 2016-01-15 16:52:31.745684502 +0000
Birth: -
tar: Documentation/scheduler: file changed as we read it
tar: Documentation/scsi: file changed as we read it
tar: Documentation/zh_CN/arm64: file changed as we read it
tar: Documentation/zh_CN/filesystems: file changed as we read it
tar: Documentation/zh_CN/video4linux: file changed as we read it
tar: Documentation: file changed as we read it
File: ‘Documentation’
Size: 15088573 Blocks: 1 IO Block: 4096 directory
Device: 23h/35d Inode: 1099511913288 Links: 1
Access: (0770/drwxrwx---) Uid: ( 1000/ XXXX) Gid: ( 1000/ XXXX)
Access: 2016-01-15 16:51:40.882143334 +0000
Modify: 2015-05-12 09:34:49.000000000 +0100
Change: 2016-01-15 16:52:31.745684502 +0000
Birth: -
I know it's possible to silence this warning with a tar option but, I
don't want to worry about that in every commands of every script, it
changes the tar output. And above all, I don't find that very clean.
Do you know any settings that guarantees that all pending async writes
are terminated when a client opens a file ?
Regards
Thomas HAMEL
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