MSL2024 LTO4 Ultr Tape Library Performance, normal or slow?

[Marlon De Ocampo]

Hi Guys,

I am a newbie with tape backups. I am the network admin here in our school. I got this tape library to replace our 960 tape drive hoping that it will increase performance. I have a dedicated server which is a Proliant DL360 G5 using U320 SCSI card. We have a gigabit network with 4 Mac servers and 4 Windows servers. I wonder if we are running normal or our performance is slow. We are backing up system state of AD and OD and the rest are data. We have a approx. 1.6TB of data to backup. I run a test and I it took almost 52 hours to finish the backup. Is this normal? is it really slow? Is it possible that we can shrink the backup time in less than 24 hours?
Thanks,
Marlon

[Pieter 't Hart]

What do you youse for backup software?

The tape drive is fast enough, but it needs constant a data rate to be sent to the drive. A single host cannot send it's data fast enough for the tape drave to run at full speed.

You need software with an agent on all backup-clients to send data in parallel (8 data streams) to the backup server.
NB! not one server at a time, but all servers in parallel
NBB! this paralel backup uses to the same tape(s) for all streams.
This may not match other wishes for backup
(like a single tape per host).

[Víctor Cespón]

The Ultrium 960 can write 80 MB/s (native) when using Ultrium 3 tapes. This means 1.6 TB in 5.5 hours.
So the limit was not the Ultrium drive. Are you copying data from the servers, reading from their hard disk, over the network? That can be very slow, specially if you're copying thousands of small files.

Run a performance test with Library and Tape tools. It will use data generated on RAM, so the HDD is not a limit.

Also you can do a test and copy from one server to your backup server hard disk. If the copy does not go at 80 MB/s at least, the tape drive is not the limit.

[Marlon De Ocampo]

We are using MSL2024 LTO4 Tape Library and yes we are copying data and files over the network.Is there anyway to speed it up? Do you mean that it will have the speed of 80MB/s if and only if the tape drive is connected to the server that it's backing up? It means that the tape library must be connected to our file server to optimize the performance? Here is our settings:

Tape Library: MSL2024 LTO4 Ultr
Dedicated server for backup: Proliant DL380
- Symantec Backup Exec 12.5
4 Mac Servers: Xserver Mac OS X Leopard
- SBE Agent for Mac
-200GB in size total
4 Windows Servers: Windows 2003
-SBE Agent for Windows
-1.4TB in size total

Current Performance: 1.6TB in 52 hours

Do you guys have any idea on how can I setup the tape backup system to gain its optimized performance?

Thanks,


All are connected to a gigabit network

[Pieter 't Hart]

even with Gigabit network at full-speed your server has at max 100MByte/sec data-throughput.
Even this number won't be reality.
apart from that your OS needs to retrieve files from the disks before it can be sent to the network.
If you're lucky you will get 20MByte/sec.
calculate this to 1.6TByte it counts up to more than 20 hours!

The tape-drive motor will start turning, write some buffered data, then stops because data comes too slow. when the buffer is filled it wil rewind a bit before starting to write again.

To have the tape-drive running at full speed you need multiple servers sending their 20MByte/sec , this is done by backup-agents.

[Víctor Cespón]

The Ultrium 960 can write 80 MB/s if the server can send them to it.

If you're copying files from another server, across a network, then the limit is not the tape drive, the data must be read from the server disk and transferred to the backup server before being writted to tape.

If the backup app is reading the files directly, then the number of files and the fragmentation level can have a big impact on the speed of the copy.

Library and Tape Tools can do performance tests on the drive and the filesystem independently. You can perform some tests, like copying to local hard disk instead of copying to tape, or copying a single big file instead of thousands of files on several folders.