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2 x Ultra 160 SDLT 320 on 1 Ultra 320 channel?

UselessUser
Frequent Advisor

2 x Ultra 160 SDLT 320 on 1 Ultra 320 channel?

Hi,

We currently have an aging ML server which has Backup Exec running. It has two separate Ultra 160 SCSI cards each connected to a HP SDLT 320 drive, it also has a Ultra 320 card connected to a HP Ultrium 960.

We are looking to move this role to a decomissioned HL DL360 G5. The only issue with this box is that it needs fibre connectivity as well as SCSI connectivity.

I have found the following PCIe adapters:

HP STORAGEWORKS U320E SCSI HOST BUS ADAPTER 320MBPS PCI EXPRESS X4 ULTRA320 SCSI STORAGE

HP STORAGEWORKS FC2242SR DUAL PORT 4.24GBPS 4GB FIBRE CHANNEL PCI EXPRESS NETWORK ADAPTER

My question is, if I move the tape drives across, I am going to have to chain the two SDLT 320 devices on a single bus because I only have two channels. Connecting the Ultrium 960 to one, and the two SDLT's to the other...

However, am I right in thinking that the more devices that share a channel, the slower the channel becomes? But then I think that I have 2 Ultra 160 devices on 1 Ultra 320 channel, so in theory I should not lose anything? Or will I because the card will "clock down" to Ultra 160 speed when it determines there are Ultra 160 devices?

Or should I not worry as the burst throughput of the SDLT is 80Mb/s not 160???

Any help would be good on this!
1 REPLY
gregersenj
Honored Contributor

Re: 2 x Ultra 160 SDLT 320 on 1 Ultra 320 channel?

Yes, that's possiblen and supportet.

Rules of Ultra wide SCSI is:
Ultra 2, Ultra 3 and Ultra 320. Each device will run at its native speed. But no faster than the max speed of the HBA.

When the hba initalizes, it will check the speed (Protocol) of each device.
The hba will start at its fasts speed. If the device can run at that speed, then that the speed of that device. If it can't. The controller will try the next lower speed.

If you put a fast wide ultra on the bus, the entire bus will run at fast wide ultra speed.