Veritas-bu

[Veritas-bu] 4 LTO Tape Drives

2003-03-08 00:10:17
Subject: [Veritas-bu] 4 LTO Tape Drives
From: mark_eisenhardt AT stoneybrookfl DOT com (Mark Eisenhardt)
Date: Sat, 8 Mar 2003 00:10:17 -0500
These are excellent backup times, but in a disaster recovery test have you
seen the restore times and do they meet the company business critical down
time?  Just wondering because we can create very fast backups and lose sight
of the amount of restore time per system in the event of losing the data
center and having to recreate at a disaster recovery site. (business
critical data only)

Sorry if I got off the original question but this can be significant. Which
is more important faster backups or restores ?
Mark Eisenhardt

-----Original Message-----
From: veritas-bu-admin AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu]On Behalf Of Jon 
Bousselot
Sent: Friday, March 07, 2003 11:14 PM
Cc: 'Karl.Rossing AT Federated DOT CA'; veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] 4 LTO Tape Drives

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



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