The only drawback to performing the Parallel method, is that you must monitor of how much tape is used over time.
This is because when it goes *over-the-edge* (at least in BackPack/RoadRunner) so it needs to write to more than the number of tapes specified, you're required to double the number of tapes used.
i.e,
If you write parallel to 2 tapes and the job wants more, even if there is only one more byte to go, you must insert 2 more tapes.
If you write parallel to 3 tapes and the job wants more, even if there is only one more byte to go, you must insert 3 more tapes.
[etc. ... and,]
If you write parallel to 6 tapes and the job wants more, even if there is only one more byte to go, you must insert 6 more tapes.
[etc.]
Obviously, when this happens, you then modify your backup job to suit your situation (write parallel to an additional tape drive, assuming you have one.)
Back to the beginning, the solution is to monitor tape usage, and add another parallel tape drive to your backup job before this occurs.
Preventive techiniques such as:
Perform a serial backup, writing to tapes in sequence every so often, so you can estimate how many tapes you really need.
i.e. If a serial backup only needs 2 tapes and you're parallel writing to 3. It may be overkill or a waste of tape, and
you should lower your parallel backup down to 2. On the other hand, if it only needs 2 tapes but it uses up most of both tapes, you're probably safer with a parallel backup of 3 tapes. Assuming your disc usage is on a constant increase.
BT
NNNN
Tracy Johnson
MSI Schaevitz Sensors
> -----Original Message-----
> From: Gilles Schipper [mailto:[log in to unmask]]
> Sent: Friday, May 03, 2002 7:21 PM
> To: [log in to unmask]
> Subject: Re: [HP3000-L] Thinking about a new tape drive
>
>
> You can actually optimize your backup by using as many as 6
> or more DDS3
> tape drives and use them in parallel.
>
> In order to take full advantage of this capability, you would
> either need
> to split the backup yourself into 6 or more backup jobs, each
> specifying
> mutually exclusive filesets - or, upgrading your backup software to
> TurboStore, from HP, or one of several 3rd-party solutions, including
> BackPack from Tymlabs, Backup+ from Orbit, or Hiback, from Hicomp.
>
> Also. you can utilize various DLT solutions.
>
> The DLT4000 is available in both SE-SCSI and FW-SCSI models.
> (Incidentally,
> on a non A-class or N-class machine, the SE-DLT4000 can be a
> boot device -
> on the A-class or N-class, the FWSCSI DLT can be a boot device.)
>
> Keep in mind the DLT4000 is not as fast as the DLT7000 or DLT8000. The
> latter 2 are available only in FWSCSI configurations and
> cannot be used as
> boot devices on your model of HP3000.
>
> As mentioned elsewhere, the DLT options are more reliable, but the
> multi-DDS3 option is also quite reliable and perhaps
> significantly less
> costly, in acquisition costs and media costs.
>
> For the multi-DDS3 option, it may be more desirable to split
> the drives
> among 2 SE-SCSI controllers, which each occupy only a half-size slot.
>
> The FWSCSI DLT drives would each require a dedicated,
> full-height FWSCSI
> controller.
>
> Finally, a single SE half-height controller can officially support 2
> DLT4000 drives.
>
>
>
> At 03:05 PM 2002-05-02, Chuck Ryan wrote:
> >I have a 939ks-020 running 6.0pp2 with a DDS3 DAT drive.
> Currently backups
> >are taking a little over 3 hours to run which is killing me
> when I try and
> >squeeze my nightly production run around it.
> >
> >What would be a good upgrade to the DAT that my system can
> keep a steady
> >stream of data into? I don't want to spend a ton of cash on
> a drive my 3000
> >cannot keep busy.
> >
> >Thanks
> >
> >* To join/leave the list, search archives, change list settings, *
> >* etc., please visit http://raven.utc.edu/archives/hp3000-l.html *
>
> --------------------------------------------------------------
> -----------------------------------
> Gilles Schipper
> GSA Inc.
> HP System Administration Specialists
> 300 John Street, Box 87651 Thornhill, ON Canada L3T 7R4
> Voice: 905.889.3000 Fax: 905.889.3001
> email: [log in to unmask] web: http://www.gsainc.com
> --------------------------------------------------------------
> -----------------------------------
>
> * To join/leave the list, search archives, change list settings, *
> * etc., please visit http://raven.utc.edu/archives/hp3000-l.html *
>
* To join/leave the list, search archives, change list settings, *
* etc., please visit http://raven.utc.edu/archives/hp3000-l.html *
|
