MSL5026 Tape Library!

[home24k]

I'm looking at the configurations of an MS5026 backup library. One of example configuration is called: "SinleMSL5026/MSL5030, 2 hosts/2drives, split sequential mode". In this configuration, the library controller is only terminated and has no cable connection to any of the drives. Each of the drives is terminated and connected to its own SCSI controller.
I have the following questions:
1. What is meant by host? Is it the SCSI card or the server?
2. What is meant by "split sequential mode"?
3. How is this configuration can be compared with the configuration where the library controller is connected to one of the drives.

Many thanks!

[Leif Halvarsson_2 · Accepted solution]

Hi,
I could not find this configuration example myself but I will try some guessing:

- Host (in this example) is the SCSI-card in the server.
- Sequential mode means that the medias is used in order (1,2,3,4....). When one media is full, the next in order is loaded. Split means that the repository is divided between the drives (for example: deive 1, media 1-15 drive 2, media 16-30).
- One important difference is that the host or application has no control over how the media is used (in which order). The library acts as one (or two if split mode) very big drives.

[Mike Naime]

Leif did a good answer of questions 1 & 2, so I will make an attempt at answering #3.

In our environment, we have our library connected by Fiber cable to our SAN. This allow several servers in our SAN to (Potentiall) send data to the same library. The library controller allows the server to control what tapes are (Randomly) inserted and read/written in each drive. you are not locked into sequential access on one specific tape drive.

[David Ruska]

I'm not familar with any manuals with that configuration example. Could you let us know what documentation you are referencing?

Leif answered most of your questions. For more info on sequential mode, see the users manual. Look under Edit/View library options (page 84):
http://h200005.www2.hp.com/bc/docs/support/SupportManual/lpg75254/lpg75254.pdf

> How is this configuration can be compared with the configuration where the library controller is connected to one of the drives.

The more typcial configuration is to daisy-chain the robotics with one of the drives, and to use a ISV backup solution (e.g. Veritas Backup Exec) to control the robotics. Usually you put the drives on separate busses, but depending on drive type you may be able to put them on a single bus (e.g. 2 DLT8K drives). If possible, use separate busses for each drive to help keep them streaming. The robot doesn't take any bus bandwidth, so it can share a bus with a drive.

Using the host to control the robitics gives you much more flexibility in how the tapes are used (in contrast to sequential mode)>

[home24k]

Thanks everyone for taking the time to answer my questions.
I'm surprise that no one came across the configuration I mentioned. I found it in the â MSL5000 Series library User Guideâ that came with the library. It can be found @ page E-4, Figure E-5.
The manual that David refer me to did not mention this configuration example.
I wonder if Iâ m I looking at an older manual and whether this configuration is still supported.

Regard

[David Ruska]

The MSL manual is on it's fifth edition, so I'm not suprised that some of the examples changed.

Yes, the sequential mode is listed in the latest version of the manual, so it should still be supported. It is a configuration that we (hp) don't test too much, as most folks are using a backup app that provides robotic control and provides much more flexibility in using your media pools.