[Kimchi-devel] [kimchi-devel][PATCH 0/6] Pool on existent VG

Thu Apr 23 18:58:47 UTC 2015

I had a few problems when testing this patchset. Below is the sequence 
of commands I tried, their outputs and my opinions. I'm running Fedora 21.

First, I tried to query the current VGs on my system:

GET /host/vgs
[
   {
     "path":"/dev/fedora",
     "name":"fedora",
     "pool":"",
     "size":"19,51g"
   }
]

That is the default VG created by the Fedora installer. The field "size" 
contains "19,51g" and I think that's not a desirable output due to these 
two reasons:

1) The value contains a unit. No other API on Kimchi returns a size 
value with a unit, the return unit is always documented. For example, in 
docs/API.md there is the following description for /storagepools/<pool>: 
"capacity: The total space which can be used to store volumes. *The unit 
is Bytes*". Notice how the unit is specified on the documentation. This 
makes it easy for the user to parse the output value because they always 
know which unit the value will be in. On Kimchi, we have the function 
"kimchi.utils.convert_data_size" which converts values from any unit to 
any other unit. I suggest we use bytes as the VG size unit as it is also 
the unit used elsewhere.

2) The value contains a comma instead of a dot. Probably that's because 
my system is using a Brazilian Portuguese locale (for context: in 
Brazilian Portuguese we use commas instead of dots to split decimal 
values, e.g. "1,5" = one and a half, unlike in English, where they use 
"1.5"). We shouldn't output different values based on the system's 
locale, otherwise, the user will never know how to parse the server's 
output. If we use bytes as the unit as suggested above, we wouldn't even 
need to use a decimal separator here, because we don't deal with values 
less than one byte anyway.

Both of the problems above are probably related to the output of "vgs". 
We should normalize that output so the user always know what to expect.

Another problem I'm having here is that I can't filter the VGs based on 
the field 'pool':

GET /host/vgs?pool='x'
[
   {
     "path":"/dev/fedora",
     "name":"fedora",
     "pool":"",
     "size":"19,51g"
   }
]

If I understand correctly, I should get an empty list here because I 
filtered for "pool=x", and the result doesn't have "pool=x".

Then I created a new VG using "vgcreate" and I queried Kimchi again:

GET /host/vgs
[
   {
     "path":"/dev/fedora",
     "name":"fedora",
     "pool":"",
     "size":"19,51g"
   },
   {
     "path":"/dev/kimchivg",
     "name":"kimchivg",
     "pool":"",
     "size":"5,00g"
   }
]

And then I created a new storage pool with that VG:

POST /storagepools/ '{"path": "kimchivg", "name": "kimchi-logical" 
"type": "logical"}'
{
   "available":0,
   "nr_volumes":0,
   "path":"/dev/kimchi-logical",
   "allocated":0,
   "capacity":0,
   "name":"kimchi-logical",
   "persistent":true,
   "source":{},
   "state":"inactive",
   "autostart":false,
   "type":"logical"
}

However, if I query the VGs again, "kimchivg" still doesn't report that 
it now belongs to "kimchi-logical":

GET /host/vgs?name='kimchivg'
[
   {
     "path":"/dev/fedora",
     "name":"fedora",
     "pool":"",
     "size":"19,51g"
   },
   {
     "path":"/dev/kimchivg",
     "name":"kimchivg",
     "pool":"",
     "size":"5,00g"
   }
]

Notice how I couldn't filter by the VG name as well. And "pool" in 
"kimchivg" is empty. As far as I understand, it should contain 
"kimchi-logical" now.

And lastly, when I tried to activate that new storage pool, I got an error:

POST /storagepools/kimchi-logical/activate
{
   "reason":"KCHPOOL0009E: Unable to activate storage pool 
kimchi-logical. Details: internal error: Child process 
(/usr/sbin/vgchange -aly kimchi-logical) unexpected exit status 5:   
Volume group \"kimchi-logical\" not found\n  Cannot process volume group 
kimchi-logical\n",
   "code":"500 Internal Server Error",
   "call_stack":"Traceback (most recent call last):\n  File 
\"/usr/lib/python2.7/site-packages/cherrypy/_cprequest.py\", line 656, 
in respond\n    response.body = self.handler()\n  File 
\"/usr/lib/python2.7/site-packages/cherrypy/lib/encoding.py\", line 188, 
in __call__\n    self.body = self.oldhandler(*args, **kwargs)\n  File 
\"/usr/lib/python2.7/site-packages/cherrypy/_cpdispatch.py\", line 34, 
in __call__\n    return self.callable(*self.args, **self.kwargs)\n  File 
\"/home/kimchi/kimchi/src/kimchi/control/base.py\", line 129, in 
wrapper\n    raise cherrypy.HTTPError(500, e.message)\nHTTPError: (500, 
u'KCHPOOL0009E: Unable to activate storage pool kimchi-logical. Details: 
internal error: Child process (/usr/sbin/vgchange -aly kimchi-logical) 
unexpected exit status 5:   Volume group \"kimchi-logical\" not 
found\\n  Cannot process volume group kimchi-logical\\n')\n"

By looking at that error message, I guess Kimchi is assuming that 
"kimchi-logical" is the VG name. Currently, when Kimchi creates the VGs 
before creating the logical storage pools, we use the VG name the same 
as the pool name. With this patchset, that may not be the case anymore; 
I have a VG named "kimchivg" and a storage pool named "kimchi-logical", 
and I believe that's the root of this error here.

Please correct me if I misunderstood something about this new patchset. 
As this is still a new feature, I may have assumed something wrong.

On 12-04-2015 11:13, lvroyce at linux.vnet.ibm.com wrote:
> From: Royce Lv <lvroyce at linux.vnet.ibm.com>
>
>
> Royce Lv (6):
>    Storagepool on existent VG: Update document
>    Add helper function to retrieve vg information
>    Update controller
>    Update model for existent VG
>    Update mockmodel tests
>    Fix fh leak in run_command subprocess
>
>   docs/API.md                            | 20 ++++++++++++++++
>   src/kimchi/control/host.py             |  6 +++++
>   src/kimchi/i18n.py                     |  2 ++
>   src/kimchi/mockmodel.py                |  9 ++++++++
>   src/kimchi/model/libvirtstoragepool.py | 11 +++++----
>   src/kimchi/model/storagepools.py       | 28 +++++++++++++----------
>   src/kimchi/model/vgs.py                | 42 ++++++++++++++++++++++++++++++++++
>   src/kimchi/utils.py                    | 22 ++++++++++++++++--
>   tests/test_mock_storagepool.py         |  9 +++++++-
>   9 files changed, 130 insertions(+), 19 deletions(-)
>   create mode 100644 src/kimchi/model/vgs.py
>

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