There are a lot of entries in
/var/log/messages of the following kind:
Dec 30 23:34:23 cs020 kernel: [177934.436173] GPT:disk_guids don't match. Dec 30 23:34:23 cs020 kernel: [177934.436177] GPT:partition_entry_array_crc32 values don't match: 0x34016b46 != 0xec291db5 Dec 30 23:34:23 cs020 kernel: [177934.436183] GPT: Use GNU Parted to correct GPT errors
The messages mean that the primary and alternate GPT headers have discrepancies.
Such situation could happen, for example, after using
dd utility on one of the partitions.
These errors could be fixed with the help of this article.
The affected ploop disk could be copied first in order to test the fix above using the following commands:
# cp -a /vz/private/CTID/root.hdd /vz/tmp/root-CTID.hdd # ploop mount /vz/tmp/root-CTID.hdd/DiskDescriptor.xml
CTID should be changed to the correct one.