You can't just say D2D.  If it's the same disk sub-system, your times
will degrade considerably because you will be doing reads and writes at
the same time.  I can push 2TB to an LTO3 tape loader in about 10 hours.
BE tells me that's 15GB/min, but in reality it's more like 3.1GB/min.

I recently bought an MD1000 from dell along with their Perc6 card and
loaded half the array with Seagate 450GB SAS
http://www.seagate.com/ww/v/index.jsp?locale=en-US&name=st3450856ss-chta
-15k.6-sas-450gb-hd&vgnextoid=056446f89a8c8110VgnVCM100000f5ee0a0aRCRD&v
gnextchannel=ef458987a7574110VgnVCM100000f5ee0a0aRCRD&reqPage=Model and
the other half with Seagate 1TB SATA's
http://www.seagate.com/ww/v/index.jsp?locale=en-US&name=barracuda-es-2-s
ata-3-0-gb/s-1-tb-hard-drive&vgnextoid=481e83de34b43110VgnVCM100000f5ee0
a0aRCRD&vgnextchannel=b655f141e7f43110VgnVCM100000f5ee0a0aRCRD&reqPage=M
odel

Make sure your math sticks with either bits or Bytes!
LSI has a SAS card that can supposedly reach 1.5GB/sec or 90GB/min!?!  A
1Gb NIC card can hit roughly 7.5GB/min

Controller card cache size, write-back/write-through all play a part.
Firmware, CPU, software used for the backup.  Backup to tape is written
differently than to disk.

I pull data from other servers over the network to a DLT drive and I get
about 575MB/min.  A one shot backup of just my exchange server over the
network to the DLT yeilds about 950MB/min.

A nightly differential of my SAS drives to the LTO3, that runs at about
400MB/min, because the data is not sequential on the drives.


HTH, and someone please check my math.  I've only had 1 cup of coffee
this morning.


Thanks,
 
Jake Gardner
TTC Network Administrator
Ext. 246

-----Original Message-----
From: Chinnery, Paul [mailto:[EMAIL PROTECTED] 
Sent: Friday, November 14, 2008 10:18 AM
To: NT System Admin Issues
Subject: RE: tape/disk speed

I'd say you definitely have an issue with backup to disk.  We do the
same thing (however, it's a SAN to SAN backup) it is considerably faster
than tape. 


Paul Chinnery
Network Administrator
Memorial Medical Center
231-845-2319

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Friday, November 14, 2008 10:13 AM
To: NT System Admin Issues
Subject: tape/disk speed


I've been doing backup to disk backups and backup to tape backups for a
long time.  I've always liked backup to disk because restores can occur
so much quicker when restoring a single file or two.  However, the other
day I was doing some testing and found that my backup to tape backups
are a LOT faster than disk.  Backing up 25GB of data to tape (LTO3)
takes me about 25 minutes at 2,855MB/min.  Backing up the same 25GB of
data to disk takes about 2 hours at 460MB/min.  

Is this what most others are seeing, or is my disk backups just
performing slow?



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