| Author |
Message |
Nico68
Guest
|
 Posted:
Fri Oct 14, 2005 5:43 pm Post subject:
Very Low SCSI performance??? |
|
|
Hi,
I am currenlty testing the writting speed of my new SCSI HDD and the
writing transfer rate are very low compare to my IDE disk.
I am using a Adaptect 29160N SCSI controller (Ultra160) and a very fast
SCSI hard drive (Hitachi, 36GB, 15k rpm, U320, LVD).
Performance are very good in read access: around 85MB/s (55MBS/s for my
IDE HDD 7.2k).
But using a simple C program base on 'fwrite' C function, I have found
that the transfer rate in writing mode is around 14MB/s for my SCSI and
around 50MB/s for my SCSI!
When I am using some benchmark program, the writing transfer is quite
good (around 80MB/s), even if I measure the time using Explorer of
Windows but my problem appears when I use a C sample program. Same
program that save few megabytes on C: (IDE) or D:(SCSI) are quite
different.
I have already test different approach as write by block of 1MB or less
or write 400MB in one block. Same result.
Does anybody know the reason why?
What could be the limitation?
I do not knwo a better way to write block of data on HDD. |
|
| Back to top |
|
 |
daytripper
Guest
|
| Posted:
Sat Oct 15, 2005 2:19 am Post subject:
Re: Very Low SCSI performance??? |
|
|
On 14 Oct 2005 05:43:39 -0700, "Nico68" <nicolas.hirbec@acquitek.com> wrote:
| Quote: | Hi,
I am currenlty testing the writting speed of my new SCSI HDD and the
writing transfer rate are very low compare to my IDE disk.
I am using a Adaptect 29160N SCSI controller (Ultra160) and a very fast
SCSI hard drive (Hitachi, 36GB, 15k rpm, U320, LVD).
Performance are very good in read access: around 85MB/s (55MBS/s for my
IDE HDD 7.2k).
But using a simple C program base on 'fwrite' C function, I have found
that the transfer rate in writing mode is around 14MB/s for my SCSI and
around 50MB/s for my SCSI!
When I am using some benchmark program, the writing transfer is quite
good (around 80MB/s), even if I measure the time using Explorer of
Windows but my problem appears when I use a C sample program. Same
program that save few megabytes on C: (IDE) or D:(SCSI) are quite
different.
I have already test different approach as write by block of 1MB or less
or write 400MB in one block. Same result.
Does anybody know the reason why?
What could be the limitation?
I do not knwo a better way to write block of data on HDD.
|
At the risk of incurring one of the resident nitwits' wrath: are the write
caches on both drives set the same? |
|
| Back to top |
|
|
Folkert Rienstra
Guest
|
| Posted:
Sat Oct 15, 2005 4:08 am Post subject:
Re: Very Low SCSI performance??? |
|
|
"daytripper" <day_trippr@REMOVEyahoo.com> wrote in message news:5680l15airdnh951o0mqrvnb6m3lhs1f23@4ax.com
| Quote: | On 14 Oct 2005 05:43:39 -0700, "Nico68" <nicolas.hirbec@acquitek.com> wrote:
Hi,
I am currenlty testing the writting speed of my new SCSI HDD and the
writing transfer rate are very low compare to my IDE disk.
I am using a Adaptect 29160N SCSI controller (Ultra160) and a very fast
SCSI hard drive (Hitachi, 36GB, 15k rpm, U320, LVD).
Performance are very good in read access: around 85MB/s (55MBS/s for my
IDE HDD 7.2k).
But using a simple C program base on 'fwrite' C function, I have found
that the transfer rate in writing mode is around 14MB/s for my SCSI and
around 50MB/s for my SCSI!
When I am using some benchmark program, the writing transfer is quite
good (around 80MB/s), even if I measure the time using Explorer of
Windows but my problem appears when I use a C sample program. Same
program that save few megabytes on C: (IDE) or D:(SCSI) are quite
different.
I have already test different approach as write by block of 1MB or less
or write 400MB in one block. Same result.
Does anybody know the reason why?
What could be the limitation?
I do not knwo a better way to write block of data on HDD.
At the risk of incurring one of the resident nitwits'
|
Don't need a nitwit for that.
| Quote: | wrath: are the write caches on both drives set the same?
|
"When I am using some benchmark program, the writing transfer is quite
good (around 80MB/s) "
What do you think, are the write caches on both drives set the same?
And that's not to assume that one can actually change the cache settings on an IDE drive. |
|
| Back to top |
|
|
daytripper
Guest
|
| Posted:
Sat Oct 15, 2005 7:02 am Post subject:
Re: Very Low SCSI performance??? |
|
|
On Sat, 15 Oct 2005 01:08:41 +0200, "Folkert Rienstra" <see_reply-to@myweb.nl>
wrote:
| Quote: | "daytripper" <day_trippr@REMOVEyahoo.com> wrote in message news:5680l15airdnh951o0mqrvnb6m3lhs1f23@4ax.com
On 14 Oct 2005 05:43:39 -0700, "Nico68" <nicolas.hirbec@acquitek.com> wrote:
Hi,
I am currenlty testing the writting speed of my new SCSI HDD and the
writing transfer rate are very low compare to my IDE disk.
I am using a Adaptect 29160N SCSI controller (Ultra160) and a very fast
SCSI hard drive (Hitachi, 36GB, 15k rpm, U320, LVD).
Performance are very good in read access: around 85MB/s (55MBS/s for my
IDE HDD 7.2k).
But using a simple C program base on 'fwrite' C function, I have found
that the transfer rate in writing mode is around 14MB/s for my SCSI and
around 50MB/s for my SCSI!
When I am using some benchmark program, the writing transfer is quite
good (around 80MB/s), even if I measure the time using Explorer of
Windows but my problem appears when I use a C sample program. Same
program that save few megabytes on C: (IDE) or D:(SCSI) are quite
different.
I have already test different approach as write by block of 1MB or less
or write 400MB in one block. Same result.
Does anybody know the reason why?
What could be the limitation?
I do not knwo a better way to write block of data on HDD.
At the risk of incurring one of the resident nitwits'
Don't need a nitwit for that.
wrath: are the write caches on both drives set the same?
"When I am using some benchmark program, the writing transfer is quite
good (around 80MB/s) "
What do you think, are the write caches on both drives set the same?
|
Who knows - there are plenty of typos in the OP's post.
Like this one:
| Quote: | But using a simple C program base on 'fwrite' C function, I have found
that the transfer rate in writing mode is around 14MB/s for my SCSI and
around 50MB/s for my SCSI!
|
So...we are left to decipher wtf he meant.
| Quote: | And that's not to assume that one can actually change the cache settings on an IDE drive.
|
So what - the question was are both drives' caches set the same or not, so
only one of them needs to be able to be changed, eh? |
|
| Back to top |
|
|
Folkert Rienstra
Guest
|
| Posted:
Sat Oct 15, 2005 4:45 pm Post subject:
Re: Very Low SCSI performance??? |
|
|
"daytripper" <day_trippr@REMOVEyahoo.com> wrote in message news:rdo0l15d4ooogrksbj07p22jtn02u4bdac@4ax.com
| Quote: | On Sat, 15 Oct 2005 01:08:41 +0200, "Folkert Rienstra" see_reply-to@myweb.nl wrote:
"daytripper" <day_trippr@REMOVEyahoo.com> wrote in message news:5680l15airdnh951o0mqrvnb6m3lhs1f23@4ax.com
On 14 Oct 2005 05:43:39 -0700, "Nico68" <nicolas.hirbec@acquitek.com> wrote:
Hi,
I am currenlty testing the writing speed of my new SCSI HDD and the
writing transfer rate is very low compared to my IDE disk.
I am using a Adaptec 29160N SCSI controller (Ultra160) and a very fast
SCSI hard drive (Hitachi, 36GB, 15k rpm, U320, LVD).
Performance is very good in read access: around 85MB/s (55MBS/s for my
IDE HDD 7.2k).
But using a simple C program based on 'fwrite' C function, I have found
that the transfer rate in writing mode is around 14MB/s for my SCSI and
around 50MB/s for my IDE HDD 7.2k !
When I am using some benchmark program, the writing transfer is quite
good (around 80MB/s), even if I measure the time using Windows Explorer
but my problem appears when I use a C sample program. Same program that
saves a few megabytes on C: (IDE) or D:(SCSI), results are quite different.
I have already tested a different approach s.a. write by block of 1MB_or_less
or write 400MB in one block. Same result.
Does anybody know the reason why?
What could be the limitation?
I do not know a better way to write block of data on HDD.
At the risk of incurring one of the resident nitwits'
Don't need a nitwit for that.
wrath: are the write caches on both drives set the same?
"When I am using some benchmark program, the writing transfer is quite
good (around 80MB/s) "
What do you think, are the write caches on both drives set the same?
Who knows - there are plenty of typos in the OP's post.
|
But they didn't obscure that
"When I am using some benchmark program, the writing transfer is quite
good (around 80MB/s) "
line in any way.
| Quote: | Like this one:
But using a simple C program base on 'fwrite' C function, I have found
that the transfer rate in writing mode is around 14MB/s for my SCSI and
around 50MB/s for my SCSI!
So...we are left to decipher wtf he meant.
|
Yeah, that one was *sooooo* difficult given that he said:
"I am currenlty testing the writting speed of my new SCSI HDD and
the writing transfer rate are very low *compare to my IDE disk*."
| Quote: |
And that's not to assume that one can actually change the cache settings on an IDE drive.
So what - the question was are both drives' caches set the same or not, so
only one of them needs to be able to be changed, eh?
|
Obviously not when the benchmark manages to write 80MB/s. |
|
| Back to top |
|
|
Nico68
Guest
|
| Posted:
Mon Oct 17, 2005 1:48 pm Post subject:
Re: Very Low SCSI performance??? |
|
|
I do not understand the meaning of your conversation. I am french and
some subtility can be miss.
However, I do not think there is a problem with cache memory. My new
SCSI disk has 14MB and my IDE is more around 2 or 8MB.
It also did not explain why the same source code with fwrite show
better performance with IDE and also why some benchmark program show
better performance with my SCSI.
Nicolas,
Folkert Rienstra a écrit :
| Quote: | "daytripper" <day_trippr@REMOVEyahoo.com> wrote in message news:rdo0l15d4ooogrksbj07p22jtn02u4bdac@4ax.com
On Sat, 15 Oct 2005 01:08:41 +0200, "Folkert Rienstra" see_reply-to@myweb.nl wrote:
"daytripper" <day_trippr@REMOVEyahoo.com> wrote in message news:5680l15airdnh951o0mqrvnb6m3lhs1f23@4ax.com
On 14 Oct 2005 05:43:39 -0700, "Nico68" <nicolas.hirbec@acquitek.com> wrote:
Hi,
I am currenlty testing the writing speed of my new SCSI HDD and the
writing transfer rate is very low compared to my IDE disk.
I am using a Adaptec 29160N SCSI controller (Ultra160) and a very fast
SCSI hard drive (Hitachi, 36GB, 15k rpm, U320, LVD).
Performance is very good in read access: around 85MB/s (55MBS/s for my
IDE HDD 7.2k).
But using a simple C program based on 'fwrite' C function, I have found
that the transfer rate in writing mode is around 14MB/s for my SCSI and
around 50MB/s for my IDE HDD 7.2k !
When I am using some benchmark program, the writing transfer is quite
good (around 80MB/s), even if I measure the time using Windows Explorer
but my problem appears when I use a C sample program. Same program that
saves a few megabytes on C: (IDE) or D:(SCSI), results are quite different.
I have already tested a different approach s.a. write by block of 1MB_or_less
or write 400MB in one block. Same result.
Does anybody know the reason why?
What could be the limitation?
I do not know a better way to write block of data on HDD.
At the risk of incurring one of the resident nitwits'
Don't need a nitwit for that.
wrath: are the write caches on both drives set the same?
"When I am using some benchmark program, the writing transfer is quite
good (around 80MB/s) "
What do you think, are the write caches on both drives set the same?
Who knows - there are plenty of typos in the OP's post.
But they didn't obscure that
"When I am using some benchmark program, the writing transfer is quite
good (around 80MB/s) "
line in any way.
Like this one:
But using a simple C program base on 'fwrite' C function, I have found
that the transfer rate in writing mode is around 14MB/s for my SCSI and
around 50MB/s for my SCSI!
So...we are left to decipher wtf he meant.
Yeah, that one was *sooooo* difficult given that he said:
"I am currenlty testing the writting speed of my new SCSI HDD and
the writing transfer rate are very low *compare to my IDE disk*."
And that's not to assume that one can actually change the cache settings on an IDE drive.
So what - the question was are both drives' caches set the same or not, so
only one of them needs to be able to be changed, eh?
Obviously not when the benchmark manages to write 80MB/s. |
|
|
| Back to top |
|
|
Folkert Rienstra
Guest
|
| Posted:
Mon Oct 17, 2005 3:53 pm Post subject:
Re: Very Low SCSI performance??? |
|
|
"Nico68" <nicolas.hirbec@acquitek.com> wrote in message news:1129538916.511972.247170@g47g2000cwa.googlegroups.com
| Quote: | I do not understand the meaning of your conversation.
|
That's OK, it wasn't meant for you. This is a newsgroup.
| Quote: | I am french and some subtility can be miss.
However, I do not think there is a problem with cache memory.
|
Right. That wasn't so hard, now was it.
| Quote: | My new SCSI disk has 14MB and my IDE is more around 2 or 8MB.
|
So? Where does it say that they not only have it but also *use* it?
That's answered by the benchmark numbers (or the settings, if you can
find them), not by the specs.
| Quote: | It also did not explain why the same source code with fwrite show
better performance with IDE and also why some benchmark program
show better performance with my SCSI.
|
That is some subtlety that is only/better explained by expert OS programmers.
You'd better ask in a software group.
| Quote: |
Nicolas,
Folkert Rienstra a écrit :
"daytripper" <day_trippr@REMOVEyahoo.com> wrote in message news:rdo0l15d4ooogrksbj07p22jtn02u4bdac@4ax.com
On Sat, 15 Oct 2005 01:08:41 +0200, "Folkert Rienstra" see_reply-to@myweb.nl wrote:
"daytripper" <day_trippr@REMOVEyahoo.com> wrote in message news:5680l15airdnh951o0mqrvnb6m3lhs1f23@4ax.com
On 14 Oct 2005 05:43:39 -0700, "Nico68" <nicolas.hirbec@acquitek.com> wrote:
Hi,
I am currenlty testing the writing speed of my new SCSI HDD and the
writing transfer rate is very low compared to my IDE disk.
I am using a Adaptec 29160N SCSI controller (Ultra160) and a very fast
SCSI hard drive (Hitachi, 36GB, 15k rpm, U320, LVD).
Performance is very good in read access: around 85MB/s (55MBS/s for my
IDE HDD 7.2k).
But using a simple C program based on 'fwrite' C function, I have found
that the transfer rate in writing mode is around 14MB/s for my SCSI and
around 50MB/s for my IDE HDD 7.2k !
When I am using some benchmark program, the writing transfer is quite
good (around 80MB/s), even if I measure the time using Windows Explorer
but my problem appears when I use a C sample program. Same program that
saves a few megabytes on C: (IDE) or D:(SCSI), results are quite different.
I have already tested a different approach s.a. write by block of 1MB_or_less
or write 400MB in one block. Same result.
Does anybody know the reason why?
What could be the limitation?
I do not know a better way to write block of data on HDD.
At the risk of incurring one of the resident nitwits'
Don't need a nitwit for that.
wrath: are the write caches on both drives set the same?
"When I am using some benchmark program, the writing transfer is quite
good (around 80MB/s) "
What do you think, are the write caches on both drives set the same?
Who knows - there are plenty of typos in the OP's post.
But they didn't obscure that
"When I am using some benchmark program, the writing transfer is quite
good (around 80MB/s) "
line in any way.
Like this one:
But using a simple C program base on 'fwrite' C function, I have found
that the transfer rate in writing mode is around 14MB/s for my SCSI and
around 50MB/s for my SCSI!
So...we are left to decipher wtf he meant.
Yeah, that one was *sooooo* difficult given that he said:
"I am currenlty testing the writting speed of my new SCSI HDD and
the writing transfer rate are very low *compare to my IDE disk*."
And that's not to assume that one can actually change the cache settings on an IDE drive.
So what - the question was are both drives' caches set the same or not, so
only one of them needs to be able to be changed, eh?
Obviously not when the benchmark manages to write 80MB/s. |
|
|
| Back to top |
|
|
Jeff Jonas
Guest
|
| Posted:
Tue Oct 18, 2005 1:34 am Post subject:
Re: Very Low SCSI performance??? |
|
|
| Quote: | But using a simple C program base on 'fwrite' C function, I have found
that the transfer rate in writing mode is around 14MB/s for my SCSI and
around 50MB/s for my SCSI!
|
fwrite uses its own buffering, fflush() forces the buffered data written.
An easier way to time a disk (using Linux or Unix) is something like
time dd if=/dev/zero of=filename bs=1m count=1000
that writes 1000 meg of zeroes and tells how long it took.
But that's STILL buffered by the system.
Write a small file and there's no disk activity until the buffer's flushed
automatically or by 'sync'. |
|
| Back to top |
|
|
Scott Lurndal
Guest
|
| Posted:
Tue Oct 18, 2005 4:35 am Post subject:
Re: Very Low SCSI performance??? |
|
|
"Nico68" <nicolas.hirbec@acquitek.com> writes:
| Quote: | Hi,
I am currenlty testing the writting speed of my new SCSI HDD and the
writing transfer rate are very low compare to my IDE disk.
I am using a Adaptect 29160N SCSI controller (Ultra160) and a very fast
SCSI hard drive (Hitachi, 36GB, 15k rpm, U320, LVD).
Performance are very good in read access: around 85MB/s (55MBS/s for my
IDE HDD 7.2k).
But using a simple C program base on 'fwrite' C function, I have found
that the transfer rate in writing mode is around 14MB/s for my SCSI and
around 50MB/s for my SCSI!
|
Don't use fwrite. When you write using the fwrite C function, you are
writting to a buffer in your application which is maintained by the
C Language runtime. When the buffer is full, the CLR will present the
buffer content to the kernel. The kernel will cache it in memory for
a while, and eventually get around to pushing it out to disk when it
needs the memory for something else.
It is impossible to determine sustained write performance using the
fwrite C routine.
The benchmarks use system calls which write directly to the device,
bypassing both application and kernel buffering.
scott |
|
| Back to top |
|
|
Scott Lurndal
Guest
|
| Posted:
Tue Oct 18, 2005 4:36 am Post subject:
Re: Very Low SCSI performance??? |
|
|
jeffj@panix.com (Jeff Jonas) writes:
| Quote: | But using a simple C program base on 'fwrite' C function, I have found
that the transfer rate in writing mode is around 14MB/s for my SCSI and
around 50MB/s for my SCSI!
fwrite uses its own buffering, fflush() forces the buffered data written.
An easier way to time a disk (using Linux or Unix) is something like
time dd if=/dev/zero of=filename bs=1m count=1000
that writes 1000 meg of zeroes and tells how long it took.
But that's STILL buffered by the system.
Write a small file and there's no disk activity until the buffer's flushed
automatically or by 'sync'.
|
Better, use open(,,O_DIRECT) and pwrite. Or on legacy unix, use the
raw device (/dev/rdsk/blah).
scott |
|
| Back to top |
|
|
The Moojit
Guest
|
| Posted:
Wed Oct 19, 2005 4:53 pm Post subject:
Re: Very Low SCSI performance??? |
|
|
I would recommend datamover for windows or datamover for Linux instead.
http://www.moojit.net
The Moojit
"Scott Lurndal" <scott@slp53.sl.home> wrote in message
news:HyW4f.3149$tV6.2869@newssvr27.news.prodigy.net...
| Quote: | "Nico68" <nicolas.hirbec@acquitek.com> writes:
Hi,
I am currenlty testing the writting speed of my new SCSI HDD and the
writing transfer rate are very low compare to my IDE disk.
I am using a Adaptect 29160N SCSI controller (Ultra160) and a very fast
SCSI hard drive (Hitachi, 36GB, 15k rpm, U320, LVD).
Performance are very good in read access: around 85MB/s (55MBS/s for my
IDE HDD 7.2k).
But using a simple C program base on 'fwrite' C function, I have found
that the transfer rate in writing mode is around 14MB/s for my SCSI and
around 50MB/s for my SCSI!
Don't use fwrite. When you write using the fwrite C function, you are
writting to a buffer in your application which is maintained by the
C Language runtime. When the buffer is full, the CLR will present the
buffer content to the kernel. The kernel will cache it in memory for
a while, and eventually get around to pushing it out to disk when it
needs the memory for something else.
It is impossible to determine sustained write performance using the
fwrite C routine.
The benchmarks use system calls which write directly to the device,
bypassing both application and kernel buffering.
scott |
|
|
| Back to top |
|
|
Folkert Rienstra
Guest
|
| Posted:
Thu Oct 20, 2005 4:19 am Post subject:
Re: Very Low SCSI performance??? |
|
|
"The Moojit" <moojit@hotmail.com> wrote in message news:3tq5f.69$GQ.13@tornado.texas.rr.com
| Quote: | I would recommend datamover for windows or datamover for Linux instead.
|
Instead of what, topposter?
| Quote: |
http://www.moojit.net
The Moojit
"Scott Lurndal" <scott@slp53.sl.home> wrote in message
news:HyW4f.3149$tV6.2869@newssvr27.news.prodigy.net...
"Nico68" <nicolas.hirbec@acquitek.com> writes:
Hi,
I am currenlty testing the writting speed of my new SCSI HDD and the
writing transfer rate are very low compare to my IDE disk.
I am using a Adaptect 29160N SCSI controller (Ultra160) and a very fast
SCSI hard drive (Hitachi, 36GB, 15k rpm, U320, LVD).
Performance are very good in read access: around 85MB/s (55MBS/s for my
IDE HDD 7.2k).
But using a simple C program base on 'fwrite' C function, I have found
that the transfer rate in writing mode is around 14MB/s for my SCSI and
around 50MB/s for my SCSI!
Don't use fwrite. When you write using the fwrite C function, you are
writting to a buffer in your application which is maintained by the
C Language runtime. When the buffer is full, the CLR will present the
buffer content to the kernel. The kernel will cache it in memory for
a while, and eventually get around to pushing it out to disk when it
needs the memory for something else.
It is impossible to determine sustained write performance using the
fwrite C routine.
The benchmarks use system calls which write directly to the device,
bypassing both application and kernel buffering.
scott |
|
|
| Back to top |
|
|
|
|
|
|
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