LTO5 Tape Drive Assistance

1 TB an hour is just a theoretical maximum, and it's always based on assuming you're getting 2:1 hardware compression.  Nobody gets these kinds of compression ratios on real data these days.  The only way you're going to be able to see better speeds than what you're seeing right now is if you do a Disk to Disk to Tape backup.  Backup Exec supports this out of the box.

This means you get a huge amount of storage which is directly attached to your Backup Server, and you back up all of your sources - simultaneously if you like - to the storage.  After that, you back it up to tape.  Backup Exec will stream all the data from the source servers, store it in large cabinet files on the Backup Storage, and then stream it all to tape.  Streaming huge files to tape will give you the fastest throughput by far, and you will be hitting huge speeds with this.  See attached image for a diagram of how this would work.

One small problem though - the bottleneck is now the network!

Gigabit Ethernet has a theoretical maximum of 125 MB/sec.  Nobody ever gets this.  Let's say 100 MB/sec for good measure, this is a very attainable average speed.

100 Megabytes a Sec = 6 Gigabytes a minute = 360 Gigabytes an hour.

If you have 2 Terabytes to back up, you could be looking at a looong backup window.

But there's light at the end of the tunnel!  People these days don't backup at night anymore - they back up CONTINUOUSLY!  I use DPM, which does synchronizations every 15 minutes to 1 hour, depending on my data type, to Disk.  This means it copies changed stuff to the disk, and everything else is skipped.  When it goes off to do the tape backups, it reads the backups it's made to disk and streams that directly to tape - SUPERFAST!

The gigabit link is no longer a bottleneck, because your backup is updating itself all the time.

Hope this has been food for thought.
BackupDiskToDiskToTape.png

Hi
The bottle-neck a disk-system of the server which  is backuped.

My issue is that whilst I never in a million years expect to get 1TB an hour, I believe it's not unreasonable to expect 1/5 of that which is 200GB an hour. I have LTO3 and LTO4 drives doing 160GB an hour and they are half height on lesser spec servers. I can't believe the SAS Disks are the bottleneck? This is a local server backup, no network.

Where do you do backup to disk to tape in backup exec?

How many Disk in the server? Raid level? what disk type?

2 x SAS 2.5" in a mirror, P410 SAS controller

2.5 SAS disk will theoretically support 60 MB/s sustained throughput

The speed of transfer of your SAS discs will mainly depend on their platters' rotational speed - a 15k rpm drive is obviously going to suck data off its discs a great deal faster than one plodding along at 5.4k.

Furthermore, compressibility of the data makes very little difference to the speed of the tape drive because the actual speed of the tape past the heads isn't usually the bottleneck, unless the drive has dirty heads or you're using bad media, and the drive is shoe-shining.

I would expect you to get at least 200GB per hour on a local backup on your current system. Is the data on the RAID badly fragmented? That would slow things down. Are you using the software compression and/or encryption option in Backup Exec? That would slow things down even more.

Have you run any tests on your system's hard disc throughput? Is the Windows 2008 fairly clean (ie, not too many programs installed, and you've turned off unneeded services)?

Do you have an anti-virus checker installed? Have you tried running the backup with it switched off?

Hi There!

Thanks for the questions tapedude.

1) These are 10K Drives.
2) Brand new tape drive, brand new media, brand new install of windows, brand new everything. I would imagine fragmentation is minimal. Not much running, just the standard HP Stuff. I need to update the PSP to the latest version. Settings in BE are as default, so I'll check, but I think it uses hardware or nothing by default, I have actually had reasonable luck with software compression vastly improving speeds on LTO4 drives, but that isn't set.

No AV at this stage.

Enabling software compression generally disables hardware compression so in effect you've slowed the tape drive down a bit, that would explain why it's a bit faster. You could always do a system performace test with HP Library and Tape Tools, that's got disk subsystem tests as well as tape drive tests.

Yah I'll try some additional tests.

I would still like to hear from someone who actually has an LTO5 and BE2010 and see what data transfer rates they are getting.

c: to tape : 1.9GB/m
c: to tape (Compression via software only) : 1054MB/M
c: to d: via B2D (compression set to software) (Partition on same mirrored hdd's) : 3.3GB/m
d: to tape : 8GB/m
d: to e: (Separate HDD on same raid controller) 5GB/m

Minimum streaming speed for a LTO-5, 47MB/sec = 2820MB/min = 2.82GB/min

If the drive IS shoe shining, then switching off the drive's hardware compression might increase the speed the tape is moving at to the point that it will stream.

Shoving some local cache on the P212 controller can also help by buffering the data so instantaneous compression gets averaged out a bit, but the only real fix is more disks in the staging pool.

We eventually got to around 4.7GB a minute, though I am unfortunately unsure exactly how, it seems like it just started working. At this stage I am not certain how to close this question

Connolly: I am not sure what you mean by minimum streaming speed?

connelly: ah never mind I see it explained in an earlier post by you.

Whilst I am not sure what the issue was, it's just a case of making the most of the answers I got.