Since u demonstrate no accurate knowledge on either the SCU program, nor the exact
details of the drive itself, even when documentation suggests otherwise, I can
still find your irresponsible replies to be unwelcome.
I'm sorry that u got burned for giving bad advice. But unlike you, I keep trying to
see the world exactly as it is, and not what one perceives it to be.
/gat
BTW your are offensive, and arrogant. This does not appear to bother you in the
slightest.
Paul Bunn wrote:
> It's neither. It's a restriction implemented in firmware. Any value of an
> interleave of anything but 1 (if supported, or not ignored) will degrade
> performance. Interleave is an age-old technique used to improve I/O performance
> back in the day when CPU/bus bandwidth was unable to process disk data quickly
> enough (and more importantly before disk drives had on-board cache).
>
> I'm surprised you're noting performance degradation when using block sizes other
> than 512 -- typically this makes little difference. It could be that the OS that
> is responsible. Or, more likely, the software you use to measure performance has
> a bug where it's assuming that a sector/block size is 512bytes. But weren't you
> the person asserting a while back that SCSI devices couldn't do different
> sector/block sizes ?
>
> No offense, but I'm growing more and more convinced that you are a living
> embodiment of the phrase "a little knowledge can be a dangerous thing".
>
> -Paul
>
> -----Original Message-----
> From: Uncle George [mailto:gatgul@voicenet.com]
> Sent: Saturday, April 28, 2001 5:33 AM
> To: Robin.Miller@Compaq.com; axp-list@redhat.com
> Subject: SCU & interleave & seagate ST15150N scsi
>
> This device does multiple blocksizes up to 4096bytes/block
>
> Going beyond 512bytes/block has a big performence hit ~1/2 of the
> 512bytes/block
>
> I tried to set the interleave in the format command, but it gave a
>
> scu> format interleave 3
> Formatting device /dev/sda (ST15150N), please be patient...
> Working ... Sat Apr 28 07:48:31 2001
> scu: 'format unit' failed on device 'ST15150N' at nexus [0/1/0]
> scu: Sense Key = 0x5 = ILLEGAL REQUEST - Illegal request or CDB
> parameter,
> Sense Code/Qualifier = (0x24, 0) = Invalid field in CDB
>
> scu> format interleave 4
> Formatting device /dev/sda (ST15150N), please be patient...
> Working ... Sat Apr 28 07:48:39 2001
> scu: 'format unit' failed on device 'ST15150N' at nexus [0/1/0]
> scu: Sense Key = 0x5 = ILLEGAL REQUEST - Illegal request or CDB
> parameter,
> Sense Code/Qualifier = (0x24, 0) = Invalid field in CDB
> scu>
>
> scu> format
> Formatting device /dev/sda (ST15150N), please be patient...
> Working ... Sat Apr 28 07:48:50 2001
> Working ... Sat Apr 28 07:50:50 2001
> Working ... Sat Apr 28 07:52:50 2001
>
> DOCUMENTATION suggests that it can do interleaves greated than 1, ie
>
> General performance characteristics
> Minimum sector interleave 1 to 1
> Data buffer to/from disc media 512-byte sector
> Data transfer rate ( 1 sector)
> Minimum 5.30 Mbytes/sec*
> Maximum 8.94 Mbytes/sec*
> Data transfer rate (< 1 track)
> Minimum, divided by interleave factor 3.56 Mbytes/sec
> Maximum, divided by interleave factor 7.65 Mbytes/sec
>
> Is it HARDWARE, or software problem. How can I tell.
>
> _______________________________________________
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