scsi or ide

[Loveless]

I ripped a ibm ddr-34560 from a old ssytem, the 68 pin singled ended version, this will be faster than my current ibm 45gb ata100 right? or should I just stick to my ide drive? I have the adatec 2940uw controller

[Kurylo]

As far as I know, your IBM ddr-34560 is a UW SCSI drive, that affords maximum bandwidth of 40MBpS. Try to check: that HDD you have (you didn't write a model) has a bandwidth 100MBpS. And that 45GB IDE HDD has greater data density which results in a higher speeds.

[Loveless]

continous 40mb per sec for my uw drive, I know that much, but from what I know, ide now days are 33mb per sec with the burst rate of 66~133mb per sec

I am probably wrong so please enlighten me

[Kurylo]

40MBpS for your SCSI and 100MBpS for IDE are the maximum interface bandwidth.
As you know, IDE and SCSI are dust interfaces of a HDD. Physically HDDs are equal. But new IDE IBM you have was made a lot earlier and comprized new know-how HDD drive technology. These upgrades result in a higher physical performance, and as a result, the whole drive performance. Even if an interface is very developed, the physical parameters of your IBM ddr-34560 are much lower.
I may say that it is indentical to running OC'ed P4 2GHz at PC133 SDRAM.
BTW, the maximum speed of my HDD was 52MBpS (tested in Sisoft Sandra 2001te). So, if I had a UW SCSI interface, it should lower the speed of my HDD as far as it handles only 40MBpS.

[Rocketmech]

You got to compare oranges with oranges...
When comparing HDD transfer performance there are two transfer rates to consider. The external (interface) transfer rate, and the internal (sustained) transfer rate(STR). For real-world transfers of average files, what we are concerned with is the rate at which the drive can transfer data sequentially from multiple tracks and cylinders on the disk to the hard disk's integrated controller and placed in the HDD cache. From here it is transfered at the rate of the HDD and/or integrated system controllers interface rate. In your case , IBM spec's the drives as follows:

DDR 34560 / 45gb (75GXP) *I'm assuming ....

8.3-13.3 / 37 Sustained Transfer Rate (MB/s)
109-171 / 444 Media data rate (Mbits/s)
7.3 / 8.5 Avg. seek time (ms)
4.33 / 4.17 Avg. Latency (ms)
384 KB / 2MB Buffer
40 / 100 External interface (MB/s)

So, as you can see, although your SCSI HDD is connected to a 40 MB/s interface its STR is only 13.3 MB/s -v- the IDE 's 37MB/s STR. And the IDE is capable of bursts of 100MB/s from the buffer if attached to an ATA100 interface , the SCSI is capable of bursts of 40mb/s.

[Loveless]

**** this sucks, I installed scsi drive for the hell of it already

[Loveless]

omfg!
the scsi scored 5000 sandra points
the ide scored 16000 sandra points

[[shawn@localhost /home]#]

AHAHAHAHAHHAHAHAH

i wouldn't install SCSI because it's WAAAAAY overpriced, a hard drive for SCSI compared to one for IDE with the exact same specs in speed and brand even, the SCSI cost twice as much (plus like the 80 bucks or whatever for SCSI card)

-Shawn

[Loveless]

hey can you guys explain average seek time?

I will probably just throw the scsi in my redhat box

[arthur888]

Maybe you can find some info on this subject here:

http://www.sysopt.com/forum/showthread.php?s=&threadid=88953&perpage=15&pagenumber=2

Average seek time is the time between the request for a sector on your HD and the beginning of the reading of it. It consists of the time for the head to get in the right position and the turning of the platter into the right position. Because SCSI and IDE drives have identical internal mechanisms in most cases, the acces times are the same for identical drives on both interfaces. Higher rpm speeds can decrease the access times but only slightly, hardly noticable. The only advantage of SCSI over IDE is that it gives lower CPU load.

[Kurylo]

From Loveless:

the scsi scored 5000 sandra points
the ide scored 16000 sandra points


That's exactly what I've said you about.