[ovirt-users] Terribly slow web consile post migration of oVirt Engine from one host to another host

Anantha Raghava raghav at exzatechconsulting.com
Thu Jun 9 17:51:10 UTC 2016


Hi,

We need to understand Postgress backup & restore process to understand 
these properly. Not having such an expertise with Postgress.

Any way, interesting discussions..worth spending time to understand it 
properly. That answers many questions....

-- 

Thanks & Regards,

Anantha Raghava


On Thursday 09 June 2016 06:41 PM, Yedidyah Bar David wrote:
> On Thu, Jun 9, 2016 at 3:33 PM, Anantha Raghava
> <raghav at exzatechconsulting.com> wrote:
>> Hi,
>>
>> Thanks for taking time and reverting back to me.
>>
>> I have seen this explanation from engine-backup help and realise that it is
>> something to do with Postgres DB restore activity. But not much said about
>> it. I feel it instructs Postgress DB to restore the DB without privileges
>> with which the object was created, but use new permissions & privileges
>> passed along with --change-db-credentials and others passed during
>> engine-backup --mode=restore.
> Exactly.
>
> And if you do not pass --change-db-credentials, you'll simply get the
> default, which is to just give permissions to the user creating the
> schema.
>
> Bottom line: If you used only defaults, and did not create users
> and give them grants, there is no difference between the options.
> They'll create the exact same database. If you did add grants, you
> must choose.
>
> I agree it's not very user-friendly to require choice, but please
> take into consideration that if you had a large setup (say hundreds
> of VMs or more) with dwh history included over some time, you'll have
> a large database, and I think it will be much less friendly if we
> "just try" restoring (which can take several hours then) and fail
> in the end due to missing users.
>
> Please also see the discussion on these bugs for more details:
>
> https://bugzilla.redhat.com/show_bug.cgi?id=1217402
> https://bugzilla.redhat.com/show_bug.cgi?id=1220791
>
> Best,
>
>> However not sure.
>>
>> --
>>
>> Thanks & Regards,
>>
>> Anantha Raghava
>> On Thursday 09 June 2016 05:47 PM, Alexander Wels wrote:
>>
>> On Thursday, June 09, 2016 12:28:41 PM Anantha Raghava wrote:
>>
>> Hello Alexander,
>>
>> You are right. The FQDN was the culprit. Once I entered the FQDN in
>> /etc/hosts file, the problem got resolved.
>>
>> Thanks for your guidance.
>>
>> By the way any document that explains what is --restore-permissions in
>> engine-backup process?
>>
>> If you type engine-backup --help you will get a list and explanation of all
>> the possible options.
>>
>> Affects only the custom dump format. Will not pass to pg_restore '--no-owner
>> --
>> no-privileges'. Might not work as expected with the --*db-user options.
>>
>> Is what the --help says, not sure what that means though.
>>
>> Hi,
>>
>> I will try both options tomorrow & revert back here.
>>
>> Regards,
>> Anantha Raghava
>>
>> On Jun 8, 2016 10:04 PM, "Alexander Wels" <awels at redhat.com
>>
>> <mailto:awels at redhat.com>> wrote:
>>      On Wednesday, June 08, 2016 08:49:16 PM Anantha Raghava wrote:
>>      > Hi,
>>      >
>>      > I was able to migrate the oVirt Engine from one host to another
>>
>>      using
>>
>>      > engine-backup utility. On the new host, the data is loaded
>>
>>      properly but
>>
>>      > the Administration Portal is terribly slow.
>>      >
>>      > It take about 2 to 3 minutes to allow me to enter user name &
>>
>>      password.
>>
>>      > Once logged in, it takes hell a lot of time to show up the data.
>>
>>      Click
>>
>>      > on a tab, we need to wait for a good amount of time to see the
>>
>>      actual
>>
>>      > data. Even the refresh is taking time to execute although it is
>>
>>      set to 5
>>
>>      > Seconds.
>>      >
>>      > But if I enable old server and connect, every thing works quickly.
>>      >
>>      > Note:
>>      >
>>      > 1. We do not have DNS in our environment.
>>      > 2. Engine name & even the IP is retained the same.
>>      > 3. Before migration, we stopped ovirt-engine on old server, took the
>>      > backup, shutdown & disconnected the old server.
>>      > 4. We installed the ovirt-engine on new server, run engine
>>
>>      setup, noted
>>
>>      > down the DB password, did engine-cleanup, restored the data using
>>      > engine-backup utility and executed engine-setup again. It did
>>
>>      recognize
>>
>>      > restored data and only httpd configuration was sought and we
>>
>>      selected
>>
>>      > the defaults.
>>
>>      It is highly likely 1 of 2 things:
>>
>>      1. The entropy mentioned by Brett, however that is mostly
>>      applicable on hosted
>>      engine as VMs don't usually have good entropy.
>>      2. The engine cannot resolve itself (which looking at your
>>      description is the
>>      likely culprit). Since you don't have DNS, you need to add the fqdn to
>>      /etc/hosts so it can resolve itself.
>>
>>      > Result is terribly slow Web Console.
>>      >
>>      > First, we attempted to setup ovirt-reports and later removed it
>>
>>      thinking
>>
>>      > that may be slowing down the engine server. Yet the same result.
>>      >
>>      > Commands used to backup from old server: "engine-backup
>>
>>      --mode=backup
>>
>>      > --file=<filename> --log=<log file name> --provision-db"
>>      > Command used to restore on new server: "engine-backup --mode=restore
>>      > --file=<backup-file-name> --log=<log-file-name>
>>
>>      --change-db-credentials
>>
>>      > --db-host=localhost --db-user=engine --db-name=engine
>>      > --db-password=<password noted down in step 4>
>>
>>      --no-restore-permissions"
>>
>>      > The command executed without any errors, resulting in a terribly
>>
>>      slow
>>
>>      > web console.
>>      >
>>      > Note: Without --restore-permissions, the restore fails. Did not
>>      > understand what to give as restore permissions. Hence used
>>      > --no-restore-permissions.
>>      >
>>      > *Hardware configuration:*
>>      > *
>>      > **Old Server:* i3 Processor, 4 GB Memory, 1 Gbps NIC
>>      > *New Server :* Lenovo x3250 M5 Server with Intel Xeon Processor,
>>
>>      16 GB
>>
>>      > RAM, 2 X 1 Gbps NIC.
>>      >
>>      > Just unable to understand why it is terribly slow.
>>
>>
>>
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>>
>
>

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