Realistically, if Array B dies, you lose the Database "and" recovery
log. The mirroring ain 't giving you protection from that.
I would separate the recovery log to array A and lose the mirroring on
both DB and log(maybe mirror log between arrays).
Restoration of a broken DB should only mean a couple hours outage, in
your case.


On Wed, 2002-10-23 at 01:03, Raghu S wrote:
> Hi,
>
> There was a lot of discussion on this topic before.But i am requesting TSM
> gurus give their comments again.
>
> The set up is like this.
>
> TSM Server : Windows NT 4.0 SP6, TSM 5.1.0.0
>
>                             392 MB memory, P III
>
>                   Adaptech Ultra SCSI
>
>                 Hard Disk :  Internal   Hardware RAID 5:
>
>                          array A : 8.678GB * 3 : 17.356GB data and 8.678 GB
> parity
>
>                          array B : 35.003 GB * 3 : 70.006GB data and 35.003
> GB parity.
>
>
> Both array A and array B are connected to the same channel.
>
> OS and TSM 5.1 are installed on array A
>
> TSM data base, recovery log and Disk storage pool are installed in array B.
>
> Database : 2GB+2GB = 4 GB  and mirrored at TSM level on the same array
>
> Recovery Log : 500MB + 500 MB = 1 GB and mirrored at TSM level on the same
> array
>
> Disk Storage pool : 10GB+10GB+10GB+10GB+5GB=45GB on array B
>
>
> TSM client: 4.1.2.12 ( Tivoli says 4.1.2.12 is not supported with 5.1
> Server. But i could take the backup,archive and restore with this
> combination )
>
> Number of Clients : 55, all are windows
>
> Incremental backup : 1GB/ client/day.
>
> backup window : 9AM to 6PM with 50% randamization ( all are in polling mode
> )
>
> LAN : 100Mbps
>
> End of the day only 10 clients could finish the backup.Remaining all are
> missing or "?" ( in progress ) or failed.
>
> Through the entire backup window the CPU load is 100% with dsmsvc.exe
> holding 98%
>
> I tested with various options. I stopped the schedular and fired 3 clients
> backup manually at the same time.Each client has 1 GB of incremental data.
> It took three hours to finish the backup. While backing up i observed there
> was lot of idletime outs of sessions.
>
> Network choke is not there. I checked this with FTP.
>
> Whats the bottleneck here? Is RAID 5 is creating problems ( DB,log and
> storage pool all are on the RAID 5 )? I asked the customer to arrange a
> testing machine without any RAID. I will be getting that in two days.Before
> going on to the testing i like to know your comments on this.
>
>
>
> Regards
>
> Raghu S Nivas
> Consultant - TSM
> DCM Data Systems Ltd
> New Delhi
> India.