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Multistreaming from a single logical drive

dp_nash
Level 3

One of my customers wants to enable multiple streams from a single logical drive on the file server.However, he cannot enable multiple streams using the NEW_STREAM directive, since the directories are dynamically created and deleted.  If we enable multi streaming setting on the client for the logical drive (C:\), how does Netbackup determine the directory inclusions in each stream ? Is this possible in the first place ?

dp_nash
1 REPLY 1

Marianne
Moderator
Moderator
Partner    VIP    Accredited Certified

As a start - Multistreaming on a single drive is never a good idea See p. 118 & 119 of Admin Guide 1 :
p. 119:
Multiple concurrent streams from a single device can adversely affect backup times.

You have a couple of choices as far as Backup Selection is concerned:
  • ALL_LOCAL_DRIVES where a job will  be spawned for each logical drive letter (a single job for c:\)
  • Explicitely specifying files/folders (will probably cause status 71's if directories are dynamically created/deleted)
  • Using wildcards: Allowing multiple datastreams with a backup selection of e.g. c:\data\* will spawn a separate backup job for each file/folder in c:\data

Backup selection options are described in above manual p. 171 under topic 'Allowing multiple data streams' and 175.

We had great success splitting up a big raid5 lun into multiple streams (data not on single physical drive):
NEW_STREAM
X:\users\a*
X:\users\b*
X:\users\c*
X:\users\d*
X:\users\e*
NEW_STREAM
X:\users\f*
X:\users\g*
X:\users\h*
X:\users\i*
X:\users\j*
X:\users\k*
NEW_STREAM
X:\users\l*
X:\users\m*
X:\users\n*
X:\users\o*
X:\users\p*

......


It took a couple of weeks to balance out the streams, but to cut a long story short, 72 hours of backing up drive X was cut down to about 12 hours.

Again - NOT recommended for single physical spindle (such as c-drive)