otheos
10-24-2001, 12:23 PM
The eternal question:
"Can I run a new ATA100 HD on my old (sic!) ATA66 controller?"
The (not so obvious) answer.
"Yes, it's backwards compatible, make sure you use tha 80core 40pin cable."
The epilogue....
"But will it be limited by the slower interface?"
The important part:
There will be absolutely no difference in performance between ATA66 and ATA100 interfaces!
ATA100 is backwards compatible with ATA66. Obviously the drive will be restricted to bursts of 66MB/s rather than 100MB/s but this has NO performance impact at all as no drive's performance reach nowhere near 66MB/s, let alone 100MB/s and bursts do not affect performance.
EDIT: don't let anyone convince you otherwise, ATA100 is hardly of any real improvement, but rather a marketing hype.
Combined bandwidth in ATA is not applicable as in SCSI:
SCSI needs as much bandwidth as possible. The fact that it has now reached 160MB/s (and soon 320MB/s) does not mean that a single drive will burst at 160MB/s and hence be fast! No! It means that when you hook up 5 hard drives that have sustained transfer rates of 30-40MB/s, they will have enough bandwith for ALL of them to send data simultaneously (ok, 5x30=150MB/s so you're within limit or there about). When you hook up a RAID array (external) with sustained rates of 100MB/s most of the bandwidth is used up. Add one more RAID array and you immediately need higher than 200MB/s bandwidth.
This is NOT the case in IDE as NO TWO devices can use the controller at the same time. So the addition of STR (sustained Transfer Rates) is not valid on IDE. When the one hard drive transfers data across, the other (slave) cannot! The max drives you may have accessing data at the same time is 2 (one per channel). So with today's IDE drives maxing STR's in the 20-40MB/s, 66MB/s is still plenty. But I hear you asking: 40+40=80MB/s so there! 66MB/s is not enough! Right? Well it's 66MB/s per channel and considering that this is a home system and not a server, the times that both drives are actually peaking in STR simultaneously for a home system are like..... few! extremely few! And then 100MB/s x 2(channels) = 200MB/s, but erm, wait, PCI 32bit 33Mhz is only 133MB/s capable.... but this is another story...
"Can I run a new ATA100 HD on my old (sic!) ATA66 controller?"
The (not so obvious) answer.
"Yes, it's backwards compatible, make sure you use tha 80core 40pin cable."
The epilogue....
"But will it be limited by the slower interface?"
The important part:
There will be absolutely no difference in performance between ATA66 and ATA100 interfaces!
ATA100 is backwards compatible with ATA66. Obviously the drive will be restricted to bursts of 66MB/s rather than 100MB/s but this has NO performance impact at all as no drive's performance reach nowhere near 66MB/s, let alone 100MB/s and bursts do not affect performance.
EDIT: don't let anyone convince you otherwise, ATA100 is hardly of any real improvement, but rather a marketing hype.
Combined bandwidth in ATA is not applicable as in SCSI:
SCSI needs as much bandwidth as possible. The fact that it has now reached 160MB/s (and soon 320MB/s) does not mean that a single drive will burst at 160MB/s and hence be fast! No! It means that when you hook up 5 hard drives that have sustained transfer rates of 30-40MB/s, they will have enough bandwith for ALL of them to send data simultaneously (ok, 5x30=150MB/s so you're within limit or there about). When you hook up a RAID array (external) with sustained rates of 100MB/s most of the bandwidth is used up. Add one more RAID array and you immediately need higher than 200MB/s bandwidth.
This is NOT the case in IDE as NO TWO devices can use the controller at the same time. So the addition of STR (sustained Transfer Rates) is not valid on IDE. When the one hard drive transfers data across, the other (slave) cannot! The max drives you may have accessing data at the same time is 2 (one per channel). So with today's IDE drives maxing STR's in the 20-40MB/s, 66MB/s is still plenty. But I hear you asking: 40+40=80MB/s so there! 66MB/s is not enough! Right? Well it's 66MB/s per channel and considering that this is a home system and not a server, the times that both drives are actually peaking in STR simultaneously for a home system are like..... few! extremely few! And then 100MB/s x 2(channels) = 200MB/s, but erm, wait, PCI 32bit 33Mhz is only 133MB/s capable.... but this is another story...