Veritas-bu

[Veritas-bu] 4 LTO Tape Drives

2003-03-10 14:40:09
Subject: [Veritas-bu] 4 LTO Tape Drives
From: Karl.Rossing AT Federated DOT CA (Karl.Rossing AT Federated DOT CA)
Date: Mon, 10 Mar 2003 13:40:09 -0600
Thanks for talking the time to answer my LTO questions.

We do multiple stream backups, each drive gets it's own single stream. 
This way we do not need to demultiplex the tapes should we have to use our 
DR site.

In the future i'd like to look into some type of catalogue replication 
scheme, this way we do not need to merge tapes. We may also look into 
burning a copy of the catalogue on a daily basis. Our catalogue right now 
is rather small.

On a complete side note, i wish there was a better way to configure shared 
memory segments when you have solaris, progress/oracle db's and netbackup 
running on the same box.

veritas-bu-admin AT mailman.eng.auburn DOT edu wrote on 03/10/2003 12:54:15 PM:

> This is something I considered greatly when designing our current backup 

> system.  Veritas puts out a book called "The Resilient Enterprise" which 

> of course does a wonderful job of promoting their products, but also 
> takes a look at case studies where these issues were either ignored or 
> anticipated.  The first few chapters cover the New York Board of Trade 
> and their offices in the WTC.  They took the time to build a backup site 

> and when the toweres crushed their datacenter and trading floor, they 
> were thankful they prepared for the worst, and realized how they should 
> have made it bigger.  Another company case study bought a 40 drive tape 
> library to augment their restore times.  I asked our Veritas rep for 
> more information about this company, but he never got back to me.  I'd 
> like to know some information about the environment that could justify 
> an additional 40 tape drives.  That's expensive!
> 
> We can successfully do high speed backups on 4 drives, and I tried to 
> buy a configuration that could support us for at least 1 or 2 years 
> without having to buy more hardware.  I wanted enough drive speed to 
> backup our whole datacenter in 4 hours, and then I added an extra 
> drive.  This is how I came to 8 LTO drives and two media servers, and 
> four gigabit lines.  We once did a restore of over a million files, and 
> because it was so many small files writing to an NT4 box, it took 13 
> hours.  For the more mission critical systems in our environment, there 
> are less files, but they are huge.  Oracle DBF files are big, and stream 

> nicely both on and off tape.  Our mission critical requirements can 
> easily be met if we had to recover a solaris/oracle database from a 
> multiplexed tape.  If we had to recover the user data from our NAS 
> server, it would take all week.  We do our best to buy and build fault 
> tolerant hardware for those systems.
> 
> I routinely test our restores to validate our process and prove the 
> reliability of our tapes.  I have worked hard to set restore 
> expectations to at least twice that of the backup times, and then I pad 
> my numbers a bit to give me time to setup and debug.  Our business would 

> suffer if we were down for a day while we recovered a database or 
> restored a filesystem.  We occasionally look at the backup load and 
> backup window to see if we are meeting the needs of the users.  It's 
> easy to get caught up in reducing the backup window, without considering 

> the restore times.  Restore speeds are never mentioned in the sales 
> brochures for any backup product I've seen.
> 
> I think if our data grows beyond our ability to effectively use 8 
> drives, we'll buy another media server and 4 more drives, so restore 
> times don't become a problem.
> 
> Since LTO's read so fast, I've found that multiplexing=8 gives me an 
> average restore stream of about 5 to 10 MB/sec, depending on the file 
> types. On the media server, I sometimes see a tape read speed of 30 - 70 

> MB/sec.
> 
> -Jon
> 
> >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
> >> 
> >>
> 
> 
> _______________________________________________
> Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu
> http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu
> 


<Prev in Thread] Current Thread [Next in Thread>