Mark,
This makes the picture a little bit different...
8*20=160MB/sec.
With an 880, plenty of CPUs and memory ~160MB/sec is about the maximum
WE could drive LTO2 tapes.
One has however to remember ther to be able to write to the tapes at
this speed the information has to come from somewhere, probably the
disks.
This means that the maximum I/O throughput that we could see was about
320MB/sec from this machine.
To be able to achieve this I/O rate we had to spread all I/Os evenly
through the two I/O busses on the 880 and separate disk and tape I/O to
different FC adapters.
You will probably have to consider an enterprise class machine that has
more I/O buses.
As regarding to sending more than one staging stream to a tape device
this is not supported.
Each staging/cloning process writes to only one output device.
Itzik
> -----Original Message-----
> From: Mark Davis [mailto:davism AT uwo DOT ca]
> Sent: Wednesday, September 28, 2005 23:44
> To: Legato NetWorker discussion; Itzik Meirson
> Subject: Re: [Networker] Migrating data from staging disk to LTO3 tape
>
> Itzik,
>
> I am presently migrating 8 file systems to 8 tape drives
> simultaneously via one Sun V880. When I said I was getting
> 10-20 MB/sec of throughput to the tape drives, I mean when
> they are all running at once.
>
> So my question really is about problems people may have had
> with LTO3's at slower data rates? And I am also wondering if
> anyone knows of a way to feed 1 tape drive with more than 1
> disk migration session?
>
> Thanks for the reply.
>
> Mark
>
> Itzik Meirson wrote:
> > Having such a limited throughput to your LTO2 drives points to very
> > slow read capability of your disk system.
> > I would suggest that first of all you figure out why your disk
> > (backup) device is not capable of providing higher read throughputs.
> > You may have to check the service time for your device and
> the total
> > throughput read+write.
> > It might very well be that if you have multiple processes (save
> > streams) writing to the same device you are reading from
> with only one
> > stream (the staging process), the writes will monopolize on
> the device.
> > I would try to test the read throughput by staging at a
> time that no
> > new backups are directed to that disk device.
> > Itzik
> >
> >
> >>-----Original Message-----
> >>From: Legato NetWorker discussion
> >>[mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU] On Behalf Of Mark Davis
> >>Sent: Wednesday, September 28, 2005 19:00
> >>To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
> >>Subject: [Networker] Migrating data from staging disk to LTO3 tape
> >>
> >>We are looking at upgrading the drives in our tape library to
> >>LTO3 technology. My concern is with cloning/migrating data from our
> >>staging drives to tape. With our present environment, the
> throughput
> >>rate to our existing LTO2 drives ranges between 10 MB/sec to 20
> >>MB/sec. With the
> >>LTO3 drives rated at 60 MB/sec, I am worried we will get into some
> >>serious "shoe shining" with the LTO3's, due to our
> inability to reach
> >>the streaming rate. This shoe shining, meaning forcing the tape to
> >>continually stop, reverse, and move forward again during recording,
> >>would cause significant wear and tear on the media and the drives.
> >>
> >>On area where I could see improvement would be to send more
> than one
> >>clone/migration session to a single tape device.
> >>Does anyone know if this is possible?
> >>
> >>Is anyone presently cloning/migrating staging disk to LTO3
> drives, and
> >>have there been any issues?
> >>
> >>Thanks very much.
> >>
> >>Mark Davis
> >>--
> >>Mark Davis
> >>Legato NetWorker Support - I.T.S
> >>University of Western Ontario
> >>email: davism AT uwo DOT ca
> >>
>
>
To sign off this list, send email to listserv AT listserv.temple DOT edu and
type "signoff networker" in the
body of the email. Please write to networker-request AT listserv.temple DOT edu
if you have any problems
wit this list. You can access the archives at
http://listserv.temple.edu/archives/networker.html or
via RSS at http://listserv.temple.edu/cgi-bin/wa?RSS&L=NETWORKER
|
