This is a collection of tips when memory is short :-).
PostgreSQL Corruption “could not read block”
If you get errors like this:
could not read block 178 in file "base/119505/119778" could not read block 21 in file "base/119505/119639"
This means the machine was not stopped properly or a filesystem problem. Once the disks and filesystems have been checked you should be able to locate and possibly repair the damage.
To find what is broken use
oid2name with the last number in the error message:
# su - postgres $ oid2name -d mailman -f 119778 From database "mailman": Filenode Table Name ------------------------ 119778 address_pkey $ oid2name -d mailman -f 119639 From database "mailman": Filenode Table Name ---------------------- 119639 user_pkey
In this example these are indexes and they can be fixed easily with:
reindex index address_pkey; reindex index user_pkey;
VM Not Booting
The VM console is accessible using
virsh console <vm_name> but if the boot
does not go that far then libguestfs comes to the rescue: the
libguestfs-rescue package on Red Hat systems) allows to access the VM’s
OS as if using a rescue media. Common tools to check the filesystem are