I must have under utilized my shift key, you are correct, for every 1Gb, you in 
theory can get 100MB/sec.
I am not sure how slow the LTO4 can write, if it cannot go slow enough there 
may be some shoe shining.
The external disks sound fine, the internals will depend on the config and 
controllers, but should be good.
Jumbo frames will be your friend.  A clear network path will be needed.

Andy Huebner

-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of 
Stef Coene
Sent: Thursday, April 30, 2009 1:49 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: [ADSM-L] backup performance on intel server

On Thursday 30 April 2009, Huebner,Andy,FORT WORTH,IT wrote:
> 1 Gb Ethernet is about 100Mb/sec
Maybe nick picking, but for me: 100Mb = 100 Mbit, 100MB is 100 MByte.

> LTO4 is about 120Mb/sec + compression
Mhh, I was counting 80 MB/s up to 160 MB/s with compression ratio 2:1.

> A good SCSI or FC drive is good for about 100Mb/sec
The disk storage fot the client is an n Series from IBM (16 TB), but also 12
TB local (scsi attached) disks.

> Assuming you can stream 3 threads across the Ethernet, you will not be able
> to keep the 3 LTO4 drives busy because of the network.  The faster tape
> drives were not intended to take data from the Ethernet. Assuming some sort
> of RAID and careful selection of file system backup times the disk can keep
> up with the network if the read is sequential and the backup software can
> find the data fast enough. Make sure you have multiple busses.  Basically I
> would look for a PCI-Express system with enough slots for the Ethernet and
> RAID or HBA controllers.
>
> I would be stressed about making the window and since you are using a
> traditional backup solution the fulls will be tough.
The customer was counting on a 24hr or even a 48hr backup window on saterday
and sunday.  And for the stress, this is solution is pushed from the head
quarters in America to the customer in Belgium.  They wanted a DS48 from IBM
+ TSM....

Thanx for the info.


Stef


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