Availability after an instance crash.

Up to now I have no experience with an instance failure of
a large database.
If you have a database say 150 Gb, and the machine has
to 'reboot', what would be a 'normal' time before the
database is available again ?
And in a worse case scenario ?
What if the OS does start a diskcheck before booting ?
(On home pc's I have seen this happening, but never
on a serious server, can this happen on a server ?)
How long will it take SQL-server to 'recover', from
a crash ?
(I am thinking of failures like a power failure or
an OS crash, not a hardware failure).
On a small testsystem where I did try this kind of
scenario's, after the OS boot, it took SQL-server only
a small time to recover (seconds).
thanks for your attention,
ben brugman.
Ben
It really depends on the perfomance of your hardware. There is no set rule that I know of for time. It also depends on what needs to be recovered and what was in the log at the time of the crash. The more of the work in the log the longer the time. It
could take anywhere from 1 minute to 45 minutes depending on how much work it has to do.
Sorry it is so vague
Jeff
MCDBA, MCSE+I
|||The recovery interval setting can impact the speed at which the =
databases will be made available.
exec sp_configure 'recovery interval (min)'
Lots more information available within Books Online (within the SQL =
Server program group). Read up on the recovery interval option.
I have not observed a checkdisk within a server based OS. I don't know =
if it could happen or not. =20
In my experience the databases are available shortly after the machine =
comes online. I have experienced a few hardware related machine crashes =
that have caused a server to black screen (become totally unresponsive). =
We had to press the power button to turn the machine off and back on =
again. Upon restarting the database was available almost right away. =
This was an OLTP database roughly 30 GB.
I have also worked with OLAP databases that were in the 150-200GB range =
that the machine became unplugged from the UPS. Upon power-up SQL =
Server was running and the databases were available in a few seconds.
The worst case scenario...you could loose your data.
A proper backup strategy is important! Make sure that you know how to =
backup and restore databases. Books Online has lots of good information =
in this area.
--=20
Keith
"ben brugman" <ben@.niethier.nl> wrote in message =
news:OTyxOZ8IEHA.3720@.tk2msftngp13.phx.gbl...
> Up to now I have no experience with an instance failure of
> a large database.
>=20
> If you have a database say 150 Gb, and the machine has
> to 'reboot', what would be a 'normal' time before the
> database is available again ?
> And in a worse case scenario ?
>=20
> What if the OS does start a diskcheck before booting ?
> (On home pc's I have seen this happening, but never
> on a serious server, can this happen on a server ?)
>=20
> How long will it take SQL-server to 'recover', from
> a crash ?
>=20
> (I am thinking of failures like a power failure or
> an OS crash, not a hardware failure).
>=20
> On a small testsystem where I did try this kind of
> scenario's, after the OS boot, it took SQL-server only
> a small time to recover (seconds).
>=20
> thanks for your attention,
> ben brugman.
>=20
>
|||Thanks Jeff and Keith,
My greatest concern was the time the OS will take on a reboot.
(And do diskchecks or other time consuming matters).
As you both indicate that you are not concerned, I'll drop this
concern.
Thanks for your answers,
Ben Brugman
"Keith Kratochvil" <sqlguy.back2u@.comcast.net> wrote in message
news:OMKoDB9IEHA.3968@.TK2MSFTNGP12.phx.gbl...
The recovery interval setting can impact the speed at which the databases
will be made available.
exec sp_configure 'recovery interval (min)'
Lots more information available within Books Online (within the SQL Server
program group). Read up on the recovery interval option.
I have not observed a checkdisk within a server based OS. I don't know if
it could happen or not.
In my experience the databases are available shortly after the machine comes
online. I have experienced a few hardware related machine crashes that have
caused a server to black screen (become totally unresponsive). We had to
press the power button to turn the machine off and back on again. Upon
restarting the database was available almost right away. This was an OLTP
database roughly 30 GB.
I have also worked with OLAP databases that were in the 150-200GB range that
the machine became unplugged from the UPS. Upon power-up SQL Server was
running and the databases were available in a few seconds.
The worst case scenario...you could loose your data.
A proper backup strategy is important! Make sure that you know how to
backup and restore databases. Books Online has lots of good information in
this area.
Keith
"ben brugman" <ben@.niethier.nl> wrote in message
news:OTyxOZ8IEHA.3720@.tk2msftngp13.phx.gbl...
> Up to now I have no experience with an instance failure of
> a large database.
> If you have a database say 150 Gb, and the machine has
> to 'reboot', what would be a 'normal' time before the
> database is available again ?
> And in a worse case scenario ?
> What if the OS does start a diskcheck before booting ?
> (On home pc's I have seen this happening, but never
> on a serious server, can this happen on a server ?)
> How long will it take SQL-server to 'recover', from
> a crash ?
> (I am thinking of failures like a power failure or
> an OS crash, not a hardware failure).
> On a small testsystem where I did try this kind of
> scenario's, after the OS boot, it took SQL-server only
> a small time to recover (seconds).
> thanks for your attention,
> ben brugman.
>