Veritas-bu

[Veritas-bu] 4 LTO Tape Drives

2003-03-07 23:14:15
Subject: [Veritas-bu] 4 LTO Tape Drives
From: jon_bousselot AT sd.vrtx DOT com (Jon Bousselot)
Date: Fri, 07 Mar 2003 20:14:15 -0800
I have two gig lines coming into each of my media servers, but one of 
them is the primary connector for backup traffic.  All the non-gig 
clients come in on the other line, so with multiplexing at 8, I can keep 
3 drives streaming, and the fourth one averages about 9 MB/sec.  This is 
the same on the other media server.  As the quick clients drop off 
toward dawn, tape usage drops down to one or two drives, and keeps a 
good stream of 8 to 18 MB/sec.  Balancing the number of data streams 
versus system load on our larger servers is more important than backup 
speed.
Our small file clients are user data NT, and our large file clients are 
Oracle databases on Sun.

Definately split the drives at two per channel.  The 64 bit 66MHz PCI 
bus on an E280 does a nice job supplying data to four drives at once. 

I did a test duplication between all drives at once, and saw average 
speeds of 15MB/sec on our four drives.  Certainly between locally 
attached units, you can really move some data!

Tuning the buffers made all the difference for streaming the 3 drives. 

-Jon

> LTO has a native speed of 15 MB/sec.  I've never seen ours burst past 
> 25 MB/sec.  So your Gigabit ethernet should be able to drive all four 
> drives at max speed.
>
> LVD SCSI is only good for 80MB/sec - I'd recommend two busses with two 
> tape drives each.
>
> $.02
> -M
>
> -----Original Message-----
> From: Karl.Rossing AT Federated DOT CA [mailto:Karl.Rossing AT Federated DOT 
> CA]
> Sent: Thursday, March 06, 2003 8:53 AM
> To: veritas-bu AT mailman.eng.auburn DOT edu
> Subject: [Veritas-bu] 4 LTO Tape Drives
>
>
> I'm thinking of getting a StorageTek L40 library with 4 LVD LTO1 tape
> drives.
>
> We don't run a SAN. We do network backups. Our backbone is a 1GB fiber.
>
> Can the 1GB fiber master server drive the 4 LTO1 drives at full speed?
> What has your experience been?
>
> Thanks,
>
> Karl 




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