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Ultrium 920 1/8 G2 Autoloader reports 160MB/S not 320

VinceL
Occasional Visitor

Ultrium 920 1/8 G2 Autoloader reports 160MB/S not 320

I have an Ultrium 920 Autoloader connected to an Adaptec 29320LPE HBA using the SCSI cable and MSKL R8000 terminator supplied with the autoloader. The HBA is set to auto terminate.

LT&T reports that the SCSI speed is only 160MB/S and hence limiting performance.

The writing on the terminator says it is an Ultra 320 LDV/SE terminator. Is this a type that will work in either differential or SE mode and does the led indicate this by changing colour, or is it just a power indicator? The led is green.

Any suggestions to determine if the speed really is only 160MB/S and if so whether it is the HBA, autoloader, cabling or termination would be appreciated.

Thanks,
Vince
5 REPLIES
TapeDrive Killer
Trusted Contributor

Re: Ultrium 920 1/8 G2 Autoloader reports 160MB/S not 320

The problem migh be that the server storage slot is 100MHz and the HBA is 133MHz.

Pablo Alvarado Siles
One drink away from sleeping on the pavement
VinceL
Occasional Visitor

Re: Ultrium 920 1/8 G2 Autoloader reports 160MB/S not 320


To quote from the motherboard manual 'The PCI Express x1 supports up to 250MB/s transfer rate.'

Does this answer your suggestion? Sorry, but bus speeds and HBAs are not really my field. I will ask our supplier to confirm.

Thanks
Vince
Curtis Ballard
Honored Contributor

Re: Ultrium 920 1/8 G2 Autoloader reports 160MB/S not 320

Getting parallel SCSI to run at U320 speeds is an art form with lots of things to check. One question to ask yourself is whether it matters to you. Most of the time with a 920 drive 160MB/s will be fast enough to keep up with a 920 drive. That drive should run about 120MB/s with 2:1 compressible data and 160 MB/s will keep up with that. If you are running about that speed or much faster then you may have highly compressible data and need the higher transfer rate. If you are getting under 120MB/s then the transfer rate is probably not limiting your performance.

The first think I always check with parallel SCSI is to pull/plug the SCSI cables and terminator at every connection several times to make certain the connections are perfectly clean. Once that is done it's a matter of testing different driver and HBA firmware revisions to see if there is a firmware issue.
VinceL
Occasional Visitor

Re: Ultrium 920 1/8 G2 Autoloader reports 160MB/S not 320

Hi

That is a good question. After consideration, it doesn't matter that much. I guess I was bullied into worrying about it by the HP diagnostics nagging about it. I was investigating why it took so long to archive a 100GB file, and saw the 160/320 warning in passing.

Having looked further, the real issue would appear to be the data transfer from the disk drives is the bottleneck and obviously not for discussion in this forum.

Having spent quite a bit on the autoloader, we should consider a higher performance machine to run it.

Thanks everyone for the advice.

Vince Leatt
VinceL
Occasional Visitor

Re: Ultrium 920 1/8 G2 Autoloader reports 160MB/S not 320

After consideration, the lack of SCSI performance was not the main issue. Even if we resolve the data bottleneck, the amount of time and effort involved in increasing the SCSI transfer rate would probably not be worth it.