Sunday, March 11, 2012

Blocking seen when two filegroups are backed up in parallel

When I backup two filegroups in parallel I see one backup
blocking the other.
eg two filegroups consisting of one data file each. Both
data files live on the f drive. One filegroup backup
writes to the h drive, the other to the i drive. Running
the backups in parallel results in one backup blocking the
other.
I suspect this is because both my data files live on the f
drive. Can anyone confirm this as the problem ?
Thanks.It's probably more to do with the fact they share the same log file and
backups need access to the logs and will put certain locks on them that
prevents some things from happening in parallel like that.
--
Andrew J. Kelly
SQL Server MVP
"anon" <anonymous@.discussions.microsoft.com> wrote in message
news:0db801c39f02$40fa1cb0$a401280a@.phx.gbl...
> When I backup two filegroups in parallel I see one backup
> blocking the other.
> eg two filegroups consisting of one data file each. Both
> data files live on the f drive. One filegroup backup
> writes to the h drive, the other to the i drive. Running
> the backups in parallel results in one backup blocking the
> other.
> I suspect this is because both my data files live on the f
> drive. Can anyone confirm this as the problem ?
> Thanks.
>|||Andrew - thanks for the reply. I think you're right.
Despite what SQL 2000 Books Online says under the
section 'Optimizing Database, Differential Database, and
File Backup Performance', I never see parallel backups.
I've now placed my two data files on different logical
drives and create the backups on two other logical drives
and still I get one backup blocked by the other.
Seems like this particular performance benefit of using
file groups doesn't really exist :( Again, nice if someone
could confirm this.
>--Original Message--
>It's probably more to do with the fact they share the
same log file and
>backups need access to the logs and will put certain
locks on them that
>prevents some things from happening in parallel like that.
>--
>Andrew J. Kelly
>SQL Server MVP
>
>"anon" <anonymous@.discussions.microsoft.com> wrote in
message
>news:0db801c39f02$40fa1cb0$a401280a@.phx.gbl...
>> When I backup two filegroups in parallel I see one
backup
>> blocking the other.
>> eg two filegroups consisting of one data file each. Both
>> data files live on the f drive. One filegroup backup
>> writes to the h drive, the other to the i drive. Running
>> the backups in parallel results in one backup blocking
the
>> other.
>> I suspect this is because both my data files live on
the f
>> drive. Can anyone confirm this as the problem ?
>> Thanks.
>
>.
>|||It can do "Parallel" backups as long as they aren't to the same database.
They are referring to backing up multiple db's at the same time.
--
Andrew J. Kelly
SQL Server MVP
"anon" <anonymous@.discussions.microsoft.com> wrote in message
news:08e001c39fa9$ea087ca0$a501280a@.phx.gbl...
> Andrew - thanks for the reply. I think you're right.
> Despite what SQL 2000 Books Online says under the
> section 'Optimizing Database, Differential Database, and
> File Backup Performance', I never see parallel backups.
> I've now placed my two data files on different logical
> drives and create the backups on two other logical drives
> and still I get one backup blocked by the other.
> Seems like this particular performance benefit of using
> file groups doesn't really exist :( Again, nice if someone
> could confirm this.
> >--Original Message--
> >It's probably more to do with the fact they share the
> same log file and
> >backups need access to the logs and will put certain
> locks on them that
> >prevents some things from happening in parallel like that.
> >
> >--
> >
> >Andrew J. Kelly
> >SQL Server MVP
> >
> >
> >"anon" <anonymous@.discussions.microsoft.com> wrote in
> message
> >news:0db801c39f02$40fa1cb0$a401280a@.phx.gbl...
> >> When I backup two filegroups in parallel I see one
> backup
> >> blocking the other.
> >>
> >> eg two filegroups consisting of one data file each. Both
> >> data files live on the f drive. One filegroup backup
> >> writes to the h drive, the other to the i drive. Running
> >> the backups in parallel results in one backup blocking
> the
> >> other.
> >>
> >> I suspect this is because both my data files live on
> the f
> >> drive. Can anyone confirm this as the problem ?
> >>
> >> Thanks.
> >>
> >
> >
> >.
> >

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