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Allow Multiple Data Streams on a policy

LeeClayton
Level 5
We use disk staging and then duplicate to tape. It's not 100% clear in the PDF's but from what I have read the option on a policy to Allow Multiple Data Streams seems to be valid only if backing up direct to Tape, so is not valid if backing up to disk (disk staging), can anyone confirm?

thanks
9 REPLIES 9

Stumpr2
Level 6
How to enable Disk Staging Storage Unit (DSSU) duplication to tape using multiple tape drives
http://support.veritas.com/docs/278169

Douglas_A
Level 6
Partner Accredited Certified
From how i understand this,

Multistreaming can be done on the original backup.

When the Duplication runs it will only run a sinlge stream i do not think you can multistream a duplication.

here is another thread that describes it a bit

www-secure.symantec.com/connect/forums/3x-faster-duplication-throughput-if-i-down-half-tape-drives-w...


LeeClayton
Level 5
maybe my question wasn't clear, the initial backup of our clients is to disk so this is where the Allow Multiple Data Streams bit comes in. I'm not trying to multistream a duplication as I know the policy is for the disk staging back to disk, just wanted to know if this flag works when backing up to disk? Thanks Doug, i think that thread you suggested will help me with another problem

Elvis_Martinez
Not applicable
Hi, I'm trying to make multiple data streams in order to backup an Oracle database using RMAN, but when I'm creating the policy,  the option "Allow multiple data streams" is disabled and others options are disabled too. I allow to check  Compression and Keyword phrase options.

Does anyone have idea why ?

Thanks !!

SteveYu
Level 4
Employee Accredited Certified
AFAIK the option does work for disk based backups however I recommend that you test the performance. Basically time the backup of a client with and without Multiple data streams to disk and more importantly test the restore. Remember allow multiple data steams is usually used with ALL_LOCAL_DRIVES which is a variable. As such you should test to determine the lower and upper boundries and it's effects. I have also listed some points below from my experience

Use example Windows client with ALL_LOCAL_DRIVES as backup selection. The Windows host is a type 2003 and has local drives C and D

Without MDS
------------------
1 job


With MDS
-------------
In my example you should get 1 parent (all_local_drives) and 3 children (C , D and Shadow copy components)


Side notes
---------------
Things I would look at are storage units, job limitations, jobs per client, master server host properties for the client. Disk i/o on the target storage unit from both testing with and without multiple data steams ( you should probably check on the client as well)



SteveYu
Level 4
Employee Accredited Certified
But from my experience if an option is greyed out it's usually because either you don't have the option licensed/installed OR it is an unsupported with some combination of the operation you are trying to perform. For example you can't do a NDMP backup to disk storage unit (well you can now but before you couldn't), it's possible that you can't use encryption option with policy type oracle backups. I suggest either opening a case or double checking the encryption guide. Personally I would check the guide first

-Sy

rjrumfelt
Level 6
in the past, and have not seen any apparent issues.  Just make sure you have enough sockets to handle all the streams (this was one of our problems, we multistreamed every single backup and then ran out of available sockets).

Amit_Karia
Level 6
Since RMAN is online backup.. You will not be able to use multistreaming as you are not backing up flat file system..All you need to do is create multiple channels in RMAN Scripts..

No of channels = no of streams

You may need to get help from Oracle Team for that

Manoj_Siricilla
Level 4
Certified
Elvis Martinez,

If you using RMAN, multiple streams have to be enabled from RMAN. This can be achieved by allocating multiple channels on the rman front which will be treated as individual jobs on netbackup front. Here is an example... (I'd used upper case only for the example)

RUN
2> {
3> ALLOCATE CHANNEL CH1 DEVICE TYPE SBT
4> PARMS 'BLKSIZE=262144'
5> ;
6> ALLOCATE CHANNEL CH2 DEVICE TYPE SBT
7> PARMS 'BLKSIZE=262144'
8> ;
9> ALLOCATE CHANNEL CH3 DEVICE TYPE SBT
10> PARMS 'BLKSIZE=262144'
11> ;
12> ALLOCATE CHANNEL CH4 DEVICE TYPE SBT
13> PARMS 'BLKSIZE=262144'
14> ;
15> ALLOCATE CHANNEL CH5 DEVICE TYPE SBT
16> PARMS 'BLKSIZE=262144'
17> ..... (commands go here, such as send, backup and so forth
.....
.....
.....
RELEASE CHANNEL CH1;
RELEASE CHANNEL CH2;
.....
.....
.....