Re: Looking for Suggestions - 5 TB DB WHSE Backup options

Both actually. Oracle suggests to set the parallelism (# of channels) for the sbt device to match the number of physical tape devices. Disable media management multiplexing because RMAN intelligently takes care of the multiplexing.

If the throughput is too low, adjustments on the RMAN side (multiplexing level, buffer size, number of buffers) can increase the amount of data coming into the media manager.

Yes, a tape device refers to the media management library you have configured in RMAN. You can have multiple physical tapes receiving data through that single RMAN tape device.

On Mon, Aug 1, 2016 at 11:46 AM, Chris Taylor < christopherdtaylor1994_at_gmail.com> wrote:

> Ok, I'm confused by the following:
>
> > Oracle suggests that no more than 1 channel be used per tape device to
> prevent inefficient writes and shoe-shining.
>
> *> "Do not utilize media management multiplexing (multiple channels per
> tape drive). RMAN backup pieces will not be efficiently restored due to the
> interleaving of pieces on the same tape volume, which may necessitate the
> forward and *
> *> backward movement of the tape."*
>
> It seems like you're saying don't allocate more than one RMAN channel per
> tape device, but the quote seems to be saying don't utilize hardware
> multiplexing channels per tape drive (Which is what I think our backup guy
> is actually suggesting we do).
>
> One more question: I assume a "tape device" (in general) contains multiple
> tapes that are loaded and available for writing?
>
> Chris
>
>
>
>
> On Mon, Aug 1, 2016 at 11:36 AM, Seth Miller <sethmiller.sm_at_gmail.com>
> wrote:
>
>> Duplexing wouldn't make much sense since that would mean copying the same
>> file to multiple destinations. He is probably referring to multiplexing or
>> parallelism. There is a difference between RMAN multiplexing and
>> parallelism and the term "stream" usually relates to the latter. RMAN
>> multiplexing allows multiple files to be read at the same time within a
>> single channel and defaults to 8. RMAN parallelism refers to multiple
>> channels writing to the same destination and is often referred to as
>> multiplexing on the media management side.
>>
>> Oracle suggests that no more than 1 channel be used per tape device to
>> prevent inefficient writes and shoe-shining.
>>
>> *"Do not utilize media management multiplexing (multiple channels per
>> tape drive). RMAN backup pieces will not be efficiently restored due to the
>> interleaving of pieces on the same tape volume, which may necessitate the
>> forward and backward movement of the tape."*
>>
>>
>> Seth Miller
>>
>>

--
http://www.freelists.org/webpage/oracle-l