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Synchronous Data transfer!

Posted on 1997-12-05
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Last Modified: 2010-04-12
I'm gonna buy a UW scsi drive soon...
can someone explain when you attain synchronous data
   transfer
can the 40 MB/s rates only be attained while copying to mem?
also...is it safe to enable write caching?

thanks
Chris
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Question by:hirbyfam
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7 Comments
 
LVL 12

Accepted Solution

by:
j2 earned 150 total points
ID: 1120722
40MB/S is an THEORETICAL value. i got a IBM DORS 2.1GB UWSCSI/3 drive, running with a AHAH2940UW controller.. and it gives about 4-6MB/sec.. 40MB/sec is the rate data is shuffled from the disks to the onboard cache ram on the disk. Write caching is safe if you can guarantee that the system wont fail (power failure etc etc)
0
 

Author Comment

by:hirbyfam
ID: 1120723
ah yes the DORS - Ultrastar ES
I'm gonna get the Ultrastar 2ES 4.3 I think - DCAS
and use a Tekram DC390F controller

thanks for answering

Chris
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LVL 12

Expert Comment

by:j2
ID: 1120724
still... dont expect anywhere NEAR 40MB/sec, 40MB/sec is the theoretical max speed of the UWSCSI bus
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Author Comment

by:hirbyfam
ID: 1120725
well yeah...
I'm interested in media streaming speeds, and sustained
   rates
I think zdnet needs to do an ultraSCSI drive test comparing
   sustained rates, even between different partitions
cuz that is mainly what I'm interested in...

cyas
0
 
LVL 12

Expert Comment

by:j2
ID: 1120726
well, then the Ultrastar is a good choice.. altough the Cheetah II vaporizes it.
0
 

Author Comment

by:hirbyfam
ID: 1120727
what about the Ultrastar 9ZX!
10,020 rpm
6.3 ms seek
17.x meg/sec minimum sustained
!!!!!!!
0
 
LVL 12

Expert Comment

by:j2
ID: 1120728
havent seen any benchmarks from an independant source yet.. but it is clearly intended as a "Cheetah killler"
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