---------- Forwarded message ----------
From: John Drescher <[EMAIL PROTECTED]>
Date: Nov 8, 2006 10:37 AM
Subject: Re: [Bacula-users] Tape access speed with LTO3
To: Adam Huffman <[EMAIL PROTECTED]>
On 11/8/06, Adam Huffman <[EMAIL PROTECTED]> wrote:
What sort of backup speed should I expect when using Bacula with an
LTO3 library?
I'm seeing nothing like the advertised 60-80MB/s.
Adam
This 60-80MB/s is the drive speed and only if your data gets a 2 to 1 compression rate as the drive writes natively at around 40MB/s. On top of this there are many factors that make archiving this rate very difficult. It is very difficult for a gigabit network to sustain 60 to 80MB/s unless you are using jumbo frames or 2 computers directly connected to each other by a single cable. Then there is the filesystem performance. The problem here is that it is very difficult to archive sustained transfers in this range even with raid because of fragmentation of the data. Even single drives do have STR rates in this range (60 to 80MB/s) but this is only if the operation is sequential and once the drive has to seek performance drops considerably. Then there is the performance of the database.
John
--
John M. Drescher
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