I have several different combinations of this going on here with mixed
results. On certain hardwares my fastest backups are writing a single
data stream but with most starting 2nd,m 3rd or even 4th simultaneous
streams is what produces the best results. I've been through the ringer
on this one, but suffice to say that every system will not be the same
so you are better off testing both. Different storage vendors handle
multiple streams in different ways, and multiple spindles vs/ drive
write speeds all create a complete mess. IMO you are better off trying
1 method, then next backup trying the next. Judge for yourself with
your specific conditions because no blanket "this way works best"
statement could possibly cover all the unknowns.
-Jonathan
________________________________
From: veritas-bu-bounces at mailman.eng.auburn.edu
[mailto:veritas-bu-bounces at mailman.eng.auburn.edu] On Behalf Of Weber,
Philip
Sent: Thursday, December 21, 2006 10:27 AM
To: Steve Fogarty; veritas-bu at mailman.eng.auburn.edu
Subject: Re: [Veritas-bu] Backup of Large Windows Volume
It's a SAN-based volume so I'm not too worried about this, we do it
elsewhere. Will have to keep an eye on it but current performance stats
indicate I should be able to get the data off the disks faster with
multiple streams.
-----Original Message-----
From: Steve Fogarty [mailto:steve.fogarty at gmail.com]
Sent: 21 December 2006 15:16
To: Weber, Philip; veritas-bu at mailman.eng.auburn.edu
Subject: RE: [Veritas-bu] Backup of Large Windows Volume
I don't think you want to have seperate streams from the same
physical disk. This is from the Admin Doc.
"For best performance, use only one data stream to back up each
physical device on the
client. Multiple concurrent streams from a single physical
device can adversely affect
backup times because the heads must move back and forth between
tracks containing files
for the respective streams."
Your selections would probably "thrash" the disk pretty hard.
Steve
________________________________
From: veritas-bu-bounces at mailman.eng.auburn.edu
[mailto:veritas-bu-bounces at mailman.eng.auburn.edu] On Behalf Of Weber,
Philip
Sent: Thursday, December 21, 2006 10:45 AM
To: veritas-bu at mailman.eng.auburn.edu
Subject: [Veritas-bu] Backup of Large Windows Volume
NetBackup 5.1 MP5, Solaris 9 master/media servers.
I have a Windows 2000 client with approx 900 Gb D: drive which I
want to split into multiple streams, e.g.
Stream 1 :
D:\Shares\shareddata\All Departments\folder1 (100 Gb)
Stream 2 :
D:\Shares\shareddata\All Departments (the rest - 130 Gb)
Stream 3 :
D:\Shares\shareddata\folder1 (160 Gb)
Stream 4 :
D:\Shares\shareddata\folder2 (52 Gb)
D:\Shares\shareddata\folder3 (52 Gb)
Stream 5 :
D:\Shares\shareddata (the rest - 270 Gb)
Stream 6 :
D:\Shares (the rest - 130 Gb)
As far as I can see I'll have to create separate policies for
all of these, in order to be able to use exclude lists to prevent
duplication of backups. Is there some way that I have missed where I
can add these all to one policy using NEW_STREAM, and not get
duplication of data?
thanks, Phil
Phil Weber
Business Technology (Egg)
Storage Technical Services - Senior UNIX Technologist
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