| Author |
Message |
Tiicount
Guest
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 Posted:
Sun Nov 06, 2005 2:13 am Post subject:
Setting up SCSI at full speed? |
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I have 2 SCSI U160 18GB LVD drives, Ultra2 WIDE interface cable +
hotplug adaptors, and an adaptec Ultra2 pci adaptor capable of 80MB/s
per channel. Unfortunately I am unable to push these drives to punch
out any more than 44.7MB/s average read. The max read I can get is
46MB/s and max burst at 58.2MB/s. The drives are set on an array TYPE 0
and do show up as the single drive as RAID, and are striped at 64kB
zeros. What am I doing wrong? With respect to the fact that 80MB/s is
only theoretical... I should still be able to achieve near this speed.
ANY ONE GOT AN IDEA??? |
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Jeremy Boden
Guest
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| Posted:
Sun Nov 06, 2005 2:56 am Post subject:
Re: Setting up SCSI at full speed? |
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In message <1131221598.833742.142870@g44g2000cwa.googlegroups.com>,
Tiicount <e_fjellgaard396@hotmail.com> writes
| Quote: | I have 2 SCSI U160 18GB LVD drives, Ultra2 WIDE interface cable +
hotplug adaptors, and an adaptec Ultra2 pci adaptor capable of 80MB/s
per channel. Unfortunately I am unable to push these drives to punch
out any more than 44.7MB/s average read. The max read I can get is
46MB/s and max burst at 58.2MB/s. The drives are set on an array TYPE 0
and do show up as the single drive as RAID, and are striped at 64kB
zeros. What am I doing wrong? With respect to the fact that 80MB/s is
only theoretical... I should still be able to achieve near this speed.
ANY ONE GOT AN IDEA???
What determines drive performance? |
Is it to do with bits of wire or the mechanics of the whole thing?
--
Jeremy Boden |
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Tiicount
Guest
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| Posted:
Sun Nov 06, 2005 6:04 am Post subject:
Re: Setting up SCSI at full speed? |
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| Quote: | What determines drive performance?
Is it to do with bits of wire or the mechanics of the whole thing?
Jeremy Boden
|
What do you mean what determines drive performance... every single
piece of my system is not just rated to run but can also perform equal
to or above 80MB/s... Thats all there is too it... unfortunately
somewhere in the setup or due to one stupid little jumper or who knows
what i cant get over 44MB/s
the drive tester i am using is HDD TACH it calculates a harddrives
specific specifications by running short tests and then gives the exact
figures on a graph mainly showing the average read... a SCSI HDD U320
is shown to have over 300MB/s max burst... not the 320 it is rated for
but damn thats close i should be able to (all technicalities
conciddered) achieve about 75MB/s max burst on any given test... WHAT
IS WRONG??? |
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Moojit
Guest
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| Posted:
Sun Nov 06, 2005 8:26 am Post subject:
Re: Setting up SCSI at full speed? |
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Try playing around with your performance tool settings. Sequential READs
will give you the best performance. Also make sure that your transfer size
is <= your drives READ cache size. This will ensure that you're not pulling
data from the media and performing cache hits only. The speeds you're
trying to achieve are wire speed, when you start to factor in the time it
takes the controller on the drive to land data to/from the media, this will
prevent you from hitting these numbers. This is why you need to tune your
application to make sure it's staying within the bounds of your drives READ
cache. WRITEs are a different story - to achieve maximum performance on
WRITEs you will need to enable WRITE BACK CACHE on your RAID controller if
it supports this type of cache. In general, performance is dependent upon
these things: o/s kernel I/O subsystem, SCSI controller driver, SCSI
controller firmware, SCSI drive firmware, and SCSI drive electro-mechanical
performance characteristics. All of these things add up to adversely affect
the wire speed limit defined by T10. Good Luck.
The Moojit
"Tiicount" <e_fjellgaard396@hotmail.com> wrote in message
news:1131221598.833742.142870@g44g2000cwa.googlegroups.com...
| Quote: | I have 2 SCSI U160 18GB LVD drives, Ultra2 WIDE interface cable +
hotplug adaptors, and an adaptec Ultra2 pci adaptor capable of 80MB/s
per channel. Unfortunately I am unable to push these drives to punch
out any more than 44.7MB/s average read. The max read I can get is
46MB/s and max burst at 58.2MB/s. The drives are set on an array TYPE 0
and do show up as the single drive as RAID, and are striped at 64kB
zeros. What am I doing wrong? With respect to the fact that 80MB/s is
only theoretical... I should still be able to achieve near this speed.
ANY ONE GOT AN IDEA???
|
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Folkert Rienstra
Guest
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| Posted:
Tue Nov 08, 2005 5:56 am Post subject:
Re: Setting up SCSI at full speed? |
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"Jeremy Boden" <jeremy@jboden.demon.co.uk> wrote in message news:kRAnQfBFyRbDFw7V@jboden.demon.co.uk
| Quote: | In message 1131221598.833742.142870@g44g2000cwa.googlegroups.com, Tiicount <e_fjellgaard396@hotmail.com> writes
I have 2 SCSI U160 18GB LVD drives, Ultra2 WIDE interface cable +
hotplug adaptors, and an adaptec Ultra2 pci adaptor capable of 80MB/s
per channel. Unfortunately I am unable to push these drives to punch
out any more than 44.7MB/s average read. The max read I can get is
46MB/s and max burst at 58.2MB/s. The drives are set on an array TYPE 0
and do show up as the single drive as RAID, and are striped at 64kB
zeros. What am I doing wrong? With respect to the fact that 80MB/s is
only theoretical... I should still be able to achieve near this speed.
ANY ONE GOT AN IDEA???
What determines drive performance?
Is it to do with bits of wire or the mechanics of the whole thing?
|
Lets see: an Ultra 160 drive is ~20MB/s or faster.
So, Raid0 is 40MB/s or faster.
What was your question again, Jeremy Boden? |
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Folkert Rienstra
Guest
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| Posted:
Tue Nov 08, 2005 5:56 am Post subject:
Re: Setting up SCSI at full speed? |
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"Tiicount" <e_fjellgaard396@hotmail.com> wrote in message news:1131221598.833742.142870@g44g2000cwa.googlegroups.com
| Quote: | I have 2 SCSI U160 18GB LVD drives, Ultra2 WIDE interface cable +
hotplug adaptors, and an adaptec Ultra2 pci adaptor capable of 80MB/s
per channel.
Unfortunately I am unable to push these drives to punch out any more
than 44.7MB/s average read.
The max read I can get is 46MB/s and max burst at 58.2MB/s.
|
Average read is too close to maximum read, suggesting that there is some limit in place.
| Quote: | The drives are set on an array TYPE 0 and do show up as the single
drive as RAID, and are striped at 64kB zeros. What am I doing wrong?
|
Not enough information.
| Quote: | With respect to the fact that 80MB/s is only theoretical...
I should still be able to achieve near this speed.
|
Nope. SCSI has ~25% overhead.
> ANY ONE GOT AN IDEA??? |
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Jeremy Boden
Guest
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| Posted:
Tue Nov 08, 2005 10:10 pm Post subject:
Re: Setting up SCSI at full speed? |
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In message <4370ac6c$1$98286$dbd45001@news.wanadoo.nl>, Folkert Rienstra
<see_Reply-To@wanadoo.nl> writes
| Quote: | "Jeremy Boden" <jeremy@jboden.demon.co.uk> wrote in message
news:kRAnQfBFyRbDFw7V@jboden.demon.co.uk
In message 1131221598.833742.142870@g44g2000cwa.googlegroups.com,
Tiicount <e_fjellgaard396@hotmail.com> writes
I have 2 SCSI U160 18GB LVD drives, Ultra2 WIDE interface cable +
hotplug adaptors, and an adaptec Ultra2 pci adaptor capable of 80MB/s
per channel. Unfortunately I am unable to push these drives to punch
out any more than 44.7MB/s average read. The max read I can get is
46MB/s and max burst at 58.2MB/s. The drives are set on an array TYPE 0
and do show up as the single drive as RAID, and are striped at 64kB
zeros. What am I doing wrong? With respect to the fact that 80MB/s is
only theoretical... I should still be able to achieve near this speed.
ANY ONE GOT AN IDEA???
What determines drive performance?
Is it to do with bits of wire or the mechanics of the whole thing?
Lets see: an Ultra 160 drive is ~20MB/s or faster.
So, Raid0 is 40MB/s or faster.
What was your question again, Jeremy Boden?
|
Are referring to the vintage of the drive or whether the electrical
connection determines performance, or indeed whether RAID is a good
thing, Folkert Rienstra?
--
Jeremy Boden |
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Folkert Rienstra
Guest
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| Posted:
Wed Nov 09, 2005 5:47 am Post subject:
Re: Setting up SCSI at full speed? |
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"Jeremy Boden" <jeremy@jboden.demon.co.uk> wrote in message news:xMdyHcAt3McDFww+@jboden.demon.co.uk
| Quote: | In message <4370ac6c$1$98286$dbd45001@news.wanadoo.nl>, Folkert Rienstra <see_Reply-To@wanadoo.nl> writes
"Jeremy Boden" jeremy@jboden.demon.co.uk> wrote in message news:kRAnQfBFyRbDFw7V@jboden.demon.co.uk
In message 1131221598.833742.142870@g44g2000cwa.googlegroups.com, Tiicount <e_fjellgaard396@hotmail.com> writes
I have 2 SCSI U160 18GB LVD drives, Ultra2 WIDE interface cable +
hotplug adaptors, and an adaptec Ultra2 pci adaptor capable of 80MB/s
per channel. Unfortunately I am unable to push these drives to punch
out any more than 44.7MB/s average read. The max read I can get is
46MB/s and max burst at 58.2MB/s. The drives are set on an array TYPE 0
and do show up as the single drive as RAID, and are striped at 64kB
zeros. What am I doing wrong? With respect to the fact that 80MB/s is
only theoretical... I should still be able to achieve near this speed.
ANY ONE GOT AN IDEA???
What determines drive performance?
Is it to do with bits of wire or the mechanics of the whole thing?
Lets see: an Ultra 160 drive is ~20MB/s or faster.
So, Raid0 is 40MB/s or faster.
What was your question again, Jeremy Boden?
Are referring to the vintage of the drive or whether the electrical
connection determines performance, or indeed whether RAID is a good
thing, Folkert Rienstra?
|
Well, 46MB/s is within normal expectation regarding that, so your answer
is what, Jeremy Boden? |
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| Back to top |
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Jeremy Boden
Guest
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| Posted:
Thu Nov 10, 2005 6:28 am Post subject:
Re: Setting up SCSI at full speed? |
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In message <437252b9$0$9379$dbd43001@news.wanadoo.nl>, Folkert Rienstra
<see_Reply-To@wanadoo.nl> writes
| Quote: | "Jeremy Boden" <jeremy@jboden.demon.co.uk> wrote in message
news:xMdyHcAt3McDFww+@jboden.demon.co.uk
In message <4370ac6c$1$98286$dbd45001@news.wanadoo.nl>, Folkert
Rienstra <see_Reply-To@wanadoo.nl> writes
"Jeremy Boden" jeremy@jboden.demon.co.uk> wrote in message
news:kRAnQfBFyRbDFw7V@jboden.demon.co.uk
In message 1131221598.833742.142870@g44g2000cwa.googlegroups.com,
Tiicount <e_fjellgaard396@hotmail.com> writes
I have 2 SCSI U160 18GB LVD drives, Ultra2 WIDE interface cable +
hotplug adaptors, and an adaptec Ultra2 pci adaptor capable of 80MB/s
per channel. Unfortunately I am unable to push these drives to punch
out any more than 44.7MB/s average read. The max read I can get is
46MB/s and max burst at 58.2MB/s. The drives are set on an array TYPE 0
and do show up as the single drive as RAID, and are striped at 64kB
zeros. What am I doing wrong? With respect to the fact that 80MB/s is
only theoretical... I should still be able to achieve near this speed.
ANY ONE GOT AN IDEA???
What determines drive performance?
Is it to do with bits of wire or the mechanics of the whole thing?
Lets see: an Ultra 160 drive is ~20MB/s or faster.
So, Raid0 is 40MB/s or faster.
What was your question again, Jeremy Boden?
Are referring to the vintage of the drive or whether the electrical
connection determines performance, or indeed whether RAID is a good
thing, Folkert Rienstra?
Well, 46MB/s is within normal expectation regarding that, so your answer
is what, Jeremy Boden?
|
Folkert, I'm not sure what your question is, but I suggest an answer
would be something like:-
For the price of all that RAID, you could have got a U160 card much more
cheaply, thereby enabling you to achieve better benchmark figures for
sequential reads.
In real life, your existing system would be unlikely to give inferior
performance to U160. In other words, performance is governed more by the
mechanics of the whole system than your bus speed.
--
Jeremy Boden |
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Folkert Rienstra
Guest
|
| Posted:
Sun Nov 13, 2005 3:09 am Post subject:
Re: Setting up SCSI at full speed? |
|
|
"Jeremy Boden" <jeremy@jboden.demon.co.uk> wrote in message news:eJup28AjQpcDFwEy@jboden.demon.co.uk
| Quote: | In message <437252b9$0$9379$dbd43001@news.wanadoo.nl>, Folkert Rienstra <see_Reply-To@wanadoo.nl> writes
"Jeremy Boden" jeremy@jboden.demon.co.uk> wrote in message news:xMdyHcAt3McDFww+@jboden.demon.co.uk
In message 4370ac6c$1$98286$dbd45001@news.wanadoo.nl>, Folkert Rienstra <see_Reply-To@wanadoo.nl> writes
"Jeremy Boden" jeremy@jboden.demon.co.uk> wrote in message news:kRAnQfBFyRbDFw7V@jboden.demon.co.uk
In message 1131221598.833742.142870@g44g2000cwa.googlegroups.com, Tiicount <e_fjellgaard396@hotmail.com> writes
I have 2 SCSI U160 18GB LVD drives, Ultra2 WIDE interface cable +
hotplug adaptors, and an adaptec Ultra2 pci adaptor capable of 80MB/s
per channel. Unfortunately I am unable to push these drives to punch
out any more than 44.7MB/s average read. The max read I can get is
46MB/s and max burst at 58.2MB/s. The drives are set on an array TYPE 0
and do show up as the single drive as RAID, and are striped at 64kB
zeros. What am I doing wrong? With respect to the fact that 80MB/s is
only theoretical... I should still be able to achieve near this speed.
ANY ONE GOT AN IDEA???
What determines drive performance?
Is it to do with bits of wire or the mechanics of the whole thing?
Lets see: an Ultra 160 drive is ~20MB/s or faster.
So, Raid0 is 40MB/s or faster.
What was your question again, Jeremy Boden?
Are referring to the vintage of the drive or whether the electrical
connection determines performance, or indeed whether RAID is a good
thing, Folkert Rienstra?
Well, 46MB/s is within normal expectation regarding that, so your answer
is what, Jeremy Boden?
Folkert, I'm not sure what your question is, but I suggest an answer
would be something like:-
For the price of all that RAID, you could have got a U160 card much more
cheaply, thereby enabling you to achieve better benchmark figures for
sequential reads.
|
Not with that drive he is using, Jeremy Boden.
The U160 card does absolutely nothing for that.
Changing to an Ultra320 drive would.,
| Quote: |
In real life, your existing system would be unlikely to give inferior
performance to U160. In other words, performance is governed more
by the mechanics of the whole system than your bus speed.
|
Whatever that mumbojumbo is supposed to mean. |
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