This seems like an expected behavior of any filesystem that isn't journaling data writes but are instead just journaling metadata updates (for speed reasons). On the start of the append operation, the file metadata is updated with the new length but the data isn't written to disk before you hard-reboot. For security reasons, the filesystem will give you zeroed out blocks. On Fri, Apr 7, 2017 at 9:36 AM, Laszlo Budai <laszlo@xxxxxxxxxxxxxxxx> wrote: > Hello, > > we have observed that there are null characters written into the open files > when hard rebooting a VM. Is tis a known issue? > Our VM is using ceph (0.94.10) storage. > we have a script like this: > while sleep 1; do date >> somefile ; done > > if we hard reset the VM while the above line is running we end up with NULL > characters in the file : > > 00000000 54 68 75 20 41 70 72 20 20 36 20 31 34 3a 33 37 |Thu Apr 6 > 14:37| > 00000010 3a 33 33 20 43 45 53 54 20 32 30 31 37 0a 54 68 |:33 CEST > 2017.Th| > 00000020 75 20 41 70 72 20 20 36 20 31 34 3a 33 37 3a 33 |u Apr 6 > 14:37:3| > 00000030 34 20 43 45 53 54 20 32 30 31 37 0a 54 68 75 20 |4 CEST 2017.Thu > | > 00000040 41 70 72 20 20 36 20 31 34 3a 33 37 3a 33 35 20 |Apr 6 14:37:35 > | > 00000050 43 45 53 54 20 32 30 31 37 0a 54 68 75 20 41 70 |CEST 2017.Thu > Ap| > 00000060 72 20 20 36 20 31 34 3a 33 37 3a 33 36 20 43 45 |r 6 14:37:36 > CE| > 00000070 53 54 20 32 30 31 37 0a 54 68 75 20 41 70 72 20 |ST 2017.Thu Apr > | > 00000080 20 36 20 31 34 3a 33 37 3a 33 39 20 43 45 53 54 | 6 14:37:39 > CEST| > 00000090 20 32 30 31 37 0a 54 68 75 20 41 70 72 20 20 36 | 2017.Thu Apr > 6| > 000000a0 20 31 34 3a 33 37 3a 34 30 20 43 45 53 54 20 32 | 14:37:40 CEST > 2| > 000000b0 30 31 37 0a 54 68 75 20 41 70 72 20 20 36 20 31 |017.Thu Apr 6 > 1| > 000000c0 34 3a 33 37 3a 34 31 20 43 45 53 54 20 32 30 31 |4:37:41 CEST > 201| > 000000d0 37 0a 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > |7...............| > 000000e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > |................| > > We've observed the same in the syslog file also. > > Any thoughts about it? > > kind regards, > Laszlo > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com -- Jason _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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