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Subject: Re: A second question ... Tablebases!

Author: Robert Hyatt

Date: 13:22:25 01/10/04

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On January 10, 2004 at 12:13:20, Lars Bremer wrote:

>On January 10, 2004 at 11:51:46, Robert Hyatt wrote:
>
>>On January 10, 2004 at 11:30:52, Lars Bremer wrote:
>>
>>>Hi,
>>>
>>>>I have to buy a new OS :-((
>>>
>>>Win2k does support HT. It handles HT as two different physical processors. WinXP
>>>can handle these virtual processors.
>>>
>>>>The biggest wish is a good Service Pack for Windows NT4 (SP7) with USB, >Directx9
>>>>and Hyperthreading support! That's all :-)
>>>
>>>It exists and is called Windows XP
>>>
>>>>BTW:
>>>>Bob do you think that SCSI is better as S-ATA (interesting for me if I used on
>>>>two harddisk 5-pieces for engine-engine matches with ponder = on on dual Xeon.
>>>>After my first test it seems that S-ATA is just great for tablebases.
>>>
>>>Lol, SATA-drives are exactly the same as PATA-drives, there are no differences.
>>>I count them twice, believe me.
>>>Normally there is only a special chip at the drive's board to convert parallel
>>>to serial.
>>>
>>>If you want to know which kind of drive is better to store and use tablebases,
>>>you should read CSS 4/03, where I compared some different hard drives under this
>>>point of view.
>>>15k-SCSI was the best, but it was not as fast as one could think, and modern
>>>ATA-drives are very fast too.
>>
>>SCSI drives offer far more than the IDE and IDE-followon SATA drives.
>>
>>(1) 320mb/sec burst transfers, double SATA, 2.5X IDE.
>
>You talking about the protocol, not about the drives. The fastest SCSI-drives
>can transfer around 75 MByte/sec, the fastest IDE-drives are close to 60
>MByte/sec now.

We are talking two different numbers.  I'm talking peak burst transfer from
on-board cache to main memory.  Not sustained data transfer rate for long
reads.

If you think your IDE drive is within 20% of a 15K scsi drive, we can run a
benchmark to compare them.  Every time I have done this, IDE simply gets
blown out of the water...  And it doesn't totally hang the system while the
drives are busy either.


>
>>(2) tagged command queueing
>
>tagged command queueing  is *not* an SCSI-feature. IBMs IDE hard disk drives can
>do that since a lot of years. Unfortunatly there is no IDE-driver to handle
>this. :)
>
>
>>which offloads the "optimizing" stuff from the
>>I/O request handler and lets the SCSI controller handle multiple requests in
>>the best possible order, something a request handler can hardly do since disk
>>drives like to "lie" about their geometry due to various compensation zones.
>>
>
>>(3) run on a SCSI and IDE system side by side.  Do something HUGE in terms of
>>I/O on both.  The scsi system will feel perfectly normal.  The IDE system
>>will basically "freeze".
>
>It depends. In a server system with a lot of small I/Os, may be. In your
>computerchess- and desktop-pc, nevermind.
>
>>There is little to recommend IDE or SATA except _price_.  That is where its
>>only advantage is seen.
>
>So you must be deaf! I never want to have a 15k-SCSI under my desk :)

I have 7 of them and they don't make much noise.  The Case fans are far
noisier.  I can barely hear the drives.  In fact, I don't notice any
difference in the 15K drives and the older 10K drives, I have both side-by-
side.

>
>>But I want performance.  And for endgame tables, the
>>faster the better.
>
>So you did measure it? What is most important? latency, transfer rate, any
>other?

Latency _and_ transfer rate.  15K offers the best latency by a factor of 2.
Transfer rate is next...  U320 SCSI wins there as well.




>
>>15K drives are great, U320 15K drives are even better.
>
>If you use only one drive there is no difference in speed between U160 and U320.

I disagree, although I have not specifically tested that.  But U320 disks
are out-performing U160 disks in two machines I have sitting side by side.
IE just doing a disk-to-disk copy of a large file...




>
>ciao
>
>Lars



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