Zitat von Carsten Jensen <to...@tomse.dk>: > Sorry for answering again, accidently hit send while not finished > > to compare an LTO4 drive with an Ultra320 controller > I get around 55MB/sec > > my guess is that the LTO3 drive should deliver around 30-40MB/sec > with the right controller (ultra320). > (pay note to that there usually are 2 models, a fast and slow one, from > each vendor) > > trying to remember back when using a 2940UW host adapter with a UW drive. > I seem to remember to get around 10MB/sec out of the drive > > so 8.8MB/sec does seem like it's what you can get out of the controller. > (I could remember wrong) > > cheers > Carsten > > On 2012-10-18 21:02, Wolfgang Denk wrote: >> Hello, >> >> apologies in advance - this may be a bit off topic, but I guess I find >> most experts for such a problem on this list... >> >> >> I see very poor performance with HP Ultrium LTO3 drive, which is >> attached over SCSI to a Linux box (using a Adaptec 2940 Ultra SCSI >> adapter). It seems I cannot get more than about 8.8 MBytes/s for >> either writing to or reading from the drive. >> >> Looking around, I see this information in /proc/scsi/aic7xxx/3 : >> >> ... >> Target 5 Negotiation Settings >> User: 40.000MB/s transfers (20.000MHz, offset 127, 16bit) >> Goal: 10.000MB/s transfers (10.000MHz, offset 15) >> Curr: 10.000MB/s transfers (10.000MHz, offset 15) >> Channel A Target 5 Lun 0 Settings >> Commands Queued 20 >> Commands Active 0 >> Command Openings 1 >> Max Tagged Openings 4 >> Device Queue Frozen Count 0 >> ... >> >> Am I understanding this correctly that the SCSI adapter is set to >> 10 MB/s transfers only? That would certainly expolain the transfer >> rates I'm observing... >> >> Is there any way to tweak these settings in Linux? I alreay checked >> in the SCSI adapter's BIOS settings, but there are no indications for >> auch a limitation. >> >> [Yes, I am aware that the Adaptec 2940 is not exactly new. But I >> should get more than 8.8 MB/s out of it, should I not?] >> >> Any help welcome. Thanks in advance. >> >> Best regards, >> >> Wolfgang Denk >>
Don't go that road. A LTO-3 FH should do around 60..80MByte/sec without compressable data, if drive compression is used i suspect it to hit the 100MByte/sec easily. Even if you SCSI controller is a 2940UW or 2940U2W you limit the drive to something around 50% of the possible speed and "shoe-shining" (http://de.wikipedia.org/wiki/Shoeshine-Problem) will happen for sure. Furthermore while in theory the tape drive should negotiate all possible SCSI variants, some newer devices fall-through if no LVD mode is possible. I suggest to buy some used U-160 or U-320 card with PCIe and let your LTO do its job. Regards Andreas ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_sfd2d_oct _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
