Slow speeds while dumping backup files to LTO-3 tape device
Hello everyone. I hope someone can help me out or at least give me a hint to how to solve this issue:
I have an arch box running the latest x86_64 arch release.
I'm using the programm "dump " http://dump.sourceforge.net/to backup to my tape device (which is an HP storageworks 920)
My scsi controller is an Intel® RAID Controller SRCU42E http://www.intel.com/design/servers/RAID/srcu42e/ controller plugged into the PCIe slot of my machine. As far as I can see it's one of the few cards for scsi devices that support Ultra 320 speeds for scsi.
The problem is that with each blocksize (from 256 up to 1024) speeds are incredibly slow.
My motherboard is: ASRock 939Dual-SATA2
My question is how to debug this whole situation,
some info on my system:
The card uses an LSI chip: http://www.lsi.com/storage_home/prod...030/index.html which uses the driver:
Fusion MPT base driver 3.04.04
Copyright (c) 1999-2007 LSI Logic Corporation
Fusion MPT SPI Host driver 3.04.04
Which I loaded manually. I also loaded the sg and the st module manually. It doesn't matter in what order I load these modules, the speed remains the same.
Anyone with any idea how to fix this? How can I make sure the controller uses it's full 320 capacity?
Any help would be great!
What's the workload on your host? Let's have a look at top (or maybe run gkrellm). Other option: Can you try to dump to another device? Maybe just a subset of the whole data, to /tmp and maybe to /dev/null. I have no experience with tape drives. But maybe you can use hdparm or something similiar to change settings of the SCSI drive.
While dumping to tape using my other (uw160) controller I get much higher speeds (35700 kB/s), system load is not the issue. I can try to dump to another device (hdd) but I'm quite sure it's something with the device and the correct drivers for it..
Since the other controller gives me much highr speeds I don't think it something with the device settings.
I have a bunch of LTO-2 and LTO-3 drives in some Netware boxes, but they're all attached to PCI-connected Adaptec 29160/39160 host adapters. The first thing the vendor told us was not to run the tape drives attached to the SCSI RAID controllers--even if on a completely separate channel.
The Asrock 939DUAL-SATA2 has a rather funky (and neat!--I have one at home--great inexpensive board) ULI chipset... I'm fairly certain no enterprise-class host adapters/RAID cards are certified to work in one.
That said, your Intel card's Ultra320 interface is way overkill for even an LTO-3 drive. Heck, Ultra160 is overkill for an LTO-3 drive w/a max transfer rate of 120 MB/s in ideal circumstances (2:1 compression, perfect relative humidity, phase of moon, etc.). PCI @ 33 MHz can provide ~266 MB/sec, so PCIX/PCIe isn't necessarily a requirement for full-speed LTO-3 operation...
If you have been able to obtain expected speeds with the Ultra160 controller you might just want to stick with that for the time being.
If you've been able to prove it's not a problem with the tape drive then I'd recommend checking out all the possible options in your intel RAID controller's BIOS options, perhaps even updating the BIOS/firmware if such an option exists. It almost sounds like there could be some kind of termination issue specific to that card...
I'm not familiar with this particular card, but there should be an option to "hard-set" the negotiation speed/rate for the LTO-3's particular ID - try capping it @ 160 and re-test etc.
Then again, I'm still unfamiliar with trying a PCIe U320 card in that board, so that may be a factor as well.
Have you attempted to contact intel/LSI support?
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