Re: NTP on linux box was ahead of 5 hrs
- From: Niall Litchfield <niall.litchfield@xxxxxxxxx>
- To: nilesh kumar <nileshkum@xxxxxxxxx>
- Date: Mon, 18 Nov 2013 16:47:26 +0000
You likely need to understand how the application works and what you are
worried about. This doesn't have a general answer.
Making the simplified assumption that everyone is in the same timezone as
the database server you still need to distinguish between code such as
"insert into time_tab(cdate) values(:dt)" and "insert into time_tab(cdate)
values(sysdate)" and "insert into time_tab(cdate) values('string from
appserver')"
On Mon, Nov 18, 2013 at 4:10 PM, nilesh kumar <nileshkum@xxxxxxxxx> wrote:
> Thanks Martijn,
>
> Suppose this database belongs to a Banking sector, and few users perform
> the transaction when NTP was 5 hrs ahead. And Suppose if user asks the
> details of their transaction in that case we are in bit confusion state
> right.
>
> In general I was checking with everyone, if someone has faced this kind of
> issue and the work around they did to fix this one.
>
> Thanks for replying Martijn
>
> Thanks
> Nilesh
>
> On Mon, Nov 18, 2013 at 8:10 PM, Martijn Bos <maboc@xxxxxxxx> wrote:
>
>> Hi,
>>
>> See my ideas inline.
>>
>> Best Regards,
>> Martijn
>>
>>
>> Best Regards,
>> Martijn
>>
>>
>> On Mon, Nov 18, 2013 at 07:03:32PM +0530, nilesh kumar wrote:
>> > Hello All,
>> >
>> > NTP was running ahead of 5 hrs of normal time on Linux box.
>> >
>> > We have oracle database running on that server version 10g.
>> >
>> > Network team tried to synchronize the NTP and they synchronized the NTP
>> on
>> > the server.
>> >
>> > >From oracle database endi have few questions.
>> >
>> > I took a levelzero backup and all archive log backup immediately and
>> asked
>> > the application team to release all the conections to the database and
>> > connection refresh so that none of the users are connected to the
>> > database, and then bounced the db and again took a level zero backup.
>> >
>> > Am i missing any thing in this case that need to be taken care.
>> >
>> > few more question in mind:-
>> > ----------------------------------------
>> >
>> > Database was running and users were connected to the database during
>> this
>> > issue occured, if some users committed the transactions and when NTP
>> was 5
>> > hrs ahead and does any inconsistency occur after the NTP was
>> synchronized.
>>
>> The database ticks around scn's so, on a 'physical' level I do not expect
>> inconsistencys.
>> On a logical level (data-model), you may expect inconsistencys when
>> 'sysdate' has been used to fill some rows.
>> (Also think of RI where sysdate is used in a column)
>>
>> >
>> > ----------------------------------------
>> > This has not occured but have a question for the below conditon.
>> > If suppose the DB would have crashed after the NTP synchronization and
>> > backup taken last sunday level zero, till what time would we able to
>> > recover the DB, as few archives have generated after when the NTP was 5
>> hrs
>> > ahead in time.
>> >
>>
>> I think that a Point In Time recovery will be a little hazardous.
>> In this case I would try to restore to a sequence number or even a scn.
>>
>> I _think_ that a restore would restore to the time before the
>> re-syncronaziation (the first time that time x appeared).
>>
>> > Please advise
>> >
>> > Thanks
>> > Nilesh
>> >
>> >
>> >
>> > --
>> > Thanks & Regards
>> > Nilesh
>> > Oracle DBA (sqlplus "/as sysdba" is my world)
>> >
>> > "As our circle of knowledge expands, so does the circumference of
>> darkness
>> > surrounding it."--Einstein
>> > "All men die, few men ever truly live" -- Braveheart
>> > "You can get help from teachers, but you are going to have to learn a
>> lot
>> > by yourself, sitting alone in a room." --Dr. Seuss
>> > "Know me for what I do and for not what I am. Judge me for what I can do
>> > and not for what I have done."-Unknown
>> > "Don't walk in front of me, I may not follow. Don't walk behind me, I
>> may
>> > not lead. Just walk beside me and be my friend."- Albert Camus
>> > "Never argue with an idiot. They drag you down to their level and then
>> beat
>> > you with experience." - Unknown
>> >
>> >
>>
>
>
>
> --
> Thanks & Regards
> Nilesh
> Oracle DBA (sqlplus "/as sysdba" is my world)
>
> "As our circle of knowledge expands, so does the circumference of darkness
> surrounding it."--Einstein
> "All men die, few men ever truly live" -- Braveheart
> "You can get help from teachers, but you are going to have to learn a lot
> by yourself, sitting alone in a room." --Dr. Seuss
> "Know me for what I do and for not what I am. Judge me for what I can do
> and not for what I have done."-Unknown
> "Don't walk in front of me, I may not follow. Don't walk behind me, I may
> not lead. Just walk beside me and be my friend."- Albert Camus
> "Never argue with an idiot. They drag you down to their level and then
> beat you with experience." - Unknown
>
--
Niall Litchfield
Oracle DBA
http://www.orawin.info
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