With my LTO3 drive, and 2x500GB sata 7200rpm drives in raid1. When I
write from disk to tape I can hit 55MB/sec max. However my dumps are
often much larger than the holding disk. I am forced to stream data to
the tape drive which slows the write.
Typical write to tape speed for a dump averages 20MB/sec. When
writing to tape I can dump 100GB in roughly 1 hr and 45 min. Im sure
with a proper config I could make my dumps more efficient. In the
amanda.conf, tape type is accurate. I think the flush-threshold
settings could use some tweaking to better utilize the limited holding
disk.
--Chad
On Dec 8, 2009, at 4:07 PM, Chris Hoogendyk wrote:
Gene Heskett wrote:
On Tuesday 08 December 2009, Charles Curley wrote:
Per Dustin's request, I did a bit of hacking on the readme. My
draft is
attached. I culled the release notes and NEWS file. I'd appreciate
comments and corrections back by the end of the business day Monday.
A few questions:
The current example of a fast dump involves filling 2 GB tapes in
four
hours.
Boy is that slow. I used ti fill a 4GB in < 2hrs.
Has anyone got a more modern example? As I don't use tapes I
can't provide one. (Several might be nice for the success stories
page,
http://wiki.zmanda.com/index.php/Amanda_success_stories.)
I have been using vtapes now for a couple of years, and a 30GB
backup is an hour & 15 mins, sometimes less.
I'm using AIT5, which has a transfer rate of 25MB/s. I'm not really
pushing it to it's limits yet. But, on a recent report, I had 41G
with 40 minutes as the reported tape time. Since I'm spreading fulls
over 7 dumps per week, the tape usage is pretty low. At the moment,
my overall backup speed is limited by some older servers that are
heavily loaded and are only connected at 100Mb. Those are all on
Solaris 9.
Someone with LTO4 would be getting around 4 times that speed or
more. I should ask the sysadmin who's running the clusters -- he's
got a large LTO4 library and a 20TB disk array that he's backing up
with Amanda. I know that he spent some time tuning his system and
was well over 100MB/s in tape speed. He's running Linux, I don't
remember for sure what distribution.
--
---------------
Chris Hoogendyk
-
O__ ---- Systems Administrator
c/ /'_ --- Biology & Geology Departments
(*) \(*) -- 140 Morrill Science Center
~~~~~~~~~~ - University of Massachusetts, Amherst
<[email protected]>
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Erdo"s 4
