Hi
I'd like to build on the great start made by Curtis and Vernon with a few
additional thoughts:
- make sure you are spreading the backup streams entering the EMC Disk Library
across the available 'front end ports' (the FC ports that connect the EDL to
your FC SAN).
- performance can also be limited by the physical disks in the storage array
itself, if you (for example) simultaneously access multiple virtual tapes that
are housed on the same physical disks. One particularly problematic use case
is a clone scenario where the tape you are reading from and the tape you are
writing to are on the same physical disks. The EDL Console will display which
LUN in the storage array each tape is housed on, so you can research why, for
example, a particular clone operation may be performing les well than others.
The EDL does apply logic to spread the virtual tapes evenly over the available
LUNs, to help spread the load evenly across the physical disks.
Hope this helps!
tl
Terry Lemons
Backup Platforms Group
EMC²
where information lives
4400 Computer Drive, MS D239
Westboro MA 01580
Phone: 508 898 7312
Email: Lemons_Terry AT emc DOT com
-----Original Message-----
From: EMC NetWorker discussion [mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU] On
Behalf Of Vernon Harris
Sent: Wednesday, October 10, 2007 1:46 PM
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Subject: Re: [Networker] Max Throughput OF EMC CDL 740
At 65 drives you are probably suffering major cpu
resource issues. You may want to throttle back to
between 40-45 drives and check your performance stats
again. Throughput will also be greatly affected by
file profile and since no SN, you are going over the
network, verify network performance, if going over the
network you will see no more than approx 80-90mB/sec
if using a single gigabit card, but since you indicate
you are seeing 160mb/sec, you must be teaming/trunking
multiple nic cards.
--- Curtis Preston <cpreston AT GLASSHOUSE DOT COM> wrote:
> While a CDL can be configured to have 65 virtual
> drives, if you're using
> all 65 virtual drives at the same time, that could
> be your problem. I'd
> suggest that you are possibly thrashing your disk
> array. Depending on
> how much you're thrashing it, you could be
> significantly reducing the
> overall effective bandwidth of your CDL. I would do
> some tests to see
> how many virtual drives you can use at a time before
> performance drops
> off. (I bet it's a lot fewer than 65.)
>
> Then you want to do cloning at the same time. You
> don't get something
> for nothing. Just like a tape library, this thing
> can only read and
> write so much data at a time. With a tape library,
> that's determine by
> the number of tape drives. With a VTL, it's
> determined by how the thing
> is architected (e.g. how much ram, cpu, and # of
> spindles). I would
> suggest talking to an SE or do some testing to see
> what those numbers
> are.
>
> ---
> W. Curtis Preston
> Backup Blog @ www.backupcentral.com
> VP Data Protection, GlassHouse Technologies
>
> -----Original Message-----
> From: EMC NetWorker discussion
> [mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU] On
> Behalf Of Leiss, Jeffrey
> Sent: Wednesday, October 10, 2007 8:36 AM
> To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
> Subject: Re: [Networker] Max Throughput OF EMC CDL
> 740
>
> Sun Solaris 10 box with no SN's. Has about 65 CDL
> drives and 5 LTO2
> drives which are used for cloning only. When backup
> are none or minimal,
> I see around 160 MB/s between the 5 drives, when box
> is loaded with
> network based backups I see 50 MB/s or less with the
> 5 LTO drves.
>
>
> -=-=-=
> Jeffrey Leiss
> Senior Infrastructure Analyst - ACS
> jeff.leiss AT nwdc DOT net
> 503.466.6540
>
>
> -----Original Message-----
> From: Fazil Saiyed [mailto:fazil.saiyed AT ANIXTER DOT COM]
> Sent: Wednesday, October 10, 2007 6:13 AM
> To: NETWORKER AT LISTSERV.TEMPLE DOT EDU; Leiss, Jeffrey
> Subject: Max Throughput OF EMC CDL 740
>
> Hello,
> I am not clear on how you have determined the speed,
> i.e while backups
> running & cloning ongoing ?
> How is your backup enviroment configured, do you
> have any existing
> storage node, what is the performance of this SN
> servers when cloning ?
> Please give us more information before any one can
> make recomendation.
> If you are CDL user SN licence may be a good option
> to have.
>
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