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Re: [Networker] Cloning parallelism
2008-01-23 11:48:52
Tim Verbois wrote:
Hello,
Environment:
VTL
L700 (LTO3 + LTO2 drives)
Legato 7.3.2 from SUN
Server + storage node
is it possible to have the parallelism on a cloning set to 2? I changed
the setting in the java interface, but it doesn't change a thing.
Why do I want to do that? We clone from VTL to L700 LTO3 tape drives.
The speed of an LTO3 drive is 70 MB/s native and can reach 100 MB when
compressed. Our VTL can supply data at a speed of 70 MB/s. A client
can do a restore at max 50 MB/s. So while we clone at a speed of 70
MB/s compressable data, we lose at least 20 MB/s average speed for
cloning. For restores, our tape is to fast, we would be satisfied with
an everage restore speed of 40MB/s.
The problem we have is that we need the top speed for cloning because of
the small time window for cloning (backupping every day and the full
weekend, needs cloning at top speeds during all the free time).
In a few weeks we start using LTO4, this is going to make the loss of
speed even bigger, much bigger. Can this be solved?
I don't see how cloning with parallelism set to 2 will help you here,
if indeed your single VTL can only do 70Mb/s. Can your VTL really run at
70Mb/s for each VTL-drive ? As a matter of fact I would expect your
performance to drop if you are going to read from two VTL-drive at the
same time as these operations tend to interfere each other. It seems
that your bottle neck is at the VTL.
--
-- Yaron.
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