[Kimchi-devel] [PATCH] issue #312: Rename LVM while deleting logical storage pool

[Royce Lv]

On 2014年03月05日 04:49, Aline Manera wrote:
> From: Aline Manera <alinefm at br.ibm.com>
>
> When creating a Logical storage pool, a LVM is created with the same
> name.
> And when deleting the storage pool the LVM keeps on the system. Which is
> the correct behavior as the storage pool is only a concept and deleting it
> should not affect the file system.
> But it prevents the user to create a new logical pool with a name used
> before which is odd.
> So when deleting a logical pool, rename the LVM to a single name to
> allow user create a logical pool with any name.
>
> Also convert an error message parameter to string instead of virStoragePool
> instance.
>
> Signed-off-by: Aline Manera <alinefm at br.ibm.com>
> ---
>   src/kimchi/model/storagepools.py |   15 ++++++++++++++-
>   1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/src/kimchi/model/storagepools.py b/src/kimchi/model/storagepools.py
> index 76ab2d6..dd3c9a2 100644
> --- a/src/kimchi/model/storagepools.py
> +++ b/src/kimchi/model/storagepools.py
> @@ -17,6 +17,8 @@
>   # License along with this library; if not, write to the Free Software
>   # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
>
> +import time
> +
>   import libvirt
>
>   from kimchi import xmlutils
> @@ -172,7 +174,8 @@ class StoragePoolModel(object):
>                   return 0
>           except libvirt.libvirtError as e:
>               raise OperationFailed("KCHPOOL0008E",
> -                                  {'name': pool, 'err': e.get_error_message()})
> +                                  {'name': pool.name(),
> +                                   'err': e.get_error_message()})
>
>       def _get_storage_source(self, pool_type, pool_xml):
>           source = {}
> @@ -348,7 +351,17 @@ class StoragePoolModel(object):
>           if pool.isActive():
>               raise InvalidOperation("KCHPOOL0005E", {'name': name})
>           try:
> +            xml = pool.XMLDesc(0)
> +            pool_type = xmlutils.xpath_get_text(xml, "/pool/@type")[0]
>               pool.undefine()
> +            # The user may want to create a logical pool with the same name
> +            # used before but a LVM will already exist with this name
> +            # So rename the former LVM to avoid future conflicts
> +            if pool_type == 'logical':
> +                lvm_name = "%s-%s" % (name, str(int(time.time()*1000)))
> +                vgrename_cmd = ["vgrename", name, lvm_name]
> +                run_command(vgrename_cmd)
Well, I would say when this VG is renamed, user would felt confused and 
wondered if it is a different VG from previous one.

Also some referrence to the LV path will change:

suppose I have a volume group called "abc" and has two LV "root" and "swap":

[lvroyce at localhost ~]$ sudo vgdisplay
--- Volume group ---
VG Name abc
System ID
Format lvm2

[lvroyce at localhost ~]$ sudo lvdisplay
--- Logical volume ---
LV Path /dev/abc/swap
LV Name swap
VG Name abc


--- Logical volume ---
LV Path /dev/abc/root
LV Name root
VG Name abc

After change the vgname from "abc" to "fedora", all its logical volumes 
path change:
[lvroyce at localhost ~]$ sudo lvdisplay
--- Logical volume ---
LV Path /dev/fedora/swap


--- Logical volume ---
LV Path /dev/fedora/root
LV Name root
VG Name fedora

This means all application depend on these volume path will be unsafe: 
e.g. a VM use an LV as its disk will not able to find its disk any more.

Based on this, I suppose maybe when storage pool type is "logical" and 
not import an existent VG,
can we validate the name is used by some VG and give out a clear indication?

> +
>           except libvirt.libvirtError as e:
>               raise OperationFailed("KCHPOOL0011E",
>                                     {'name': name, 'err': e.get_error_message()})