Does SATA allow simultanous drive access?

[westrock2000]

I dont know what the actual term for this is, but I did try to google it.

Back in the day when it was IDE vs SCSI, what I though was the biggest advantage to SCSI was that each drive could be accessed simultanously. So for instance, in all SCSI system, you could install a game from CD to HDD 1 and listen to music from HDD 2 and there was no slowdown. Where as you probably remember the old IDE days where the CD light would blink for a little bit, then the HDD light would blink, then the CD, then the HDD....but not together.

So I have not really noticed this issue in a long time. Did SATA do away with this issue? I'm guessing so since alot of us have 4-6 drives attached to our SATA buses.

Thanks for helping the newb.

 

[sub.mesa]

SCSI has Tagged Command Queueing (TCQ)
SATA has Native Command queueing (NCQ)

NCQ requires AHCI mode so is not available in IDE legacy mode. With NCQ you can send up to 32 queued I/O's; which in theory could be processed by the HDD all at once.

But HDDs are serial devices; they can only do one physical operation at any one time. SSDs are parallel devices and thus NCQ can cause them to scale linearly with the number of outstanding queues. For example, when using NCQ the Intel SSDs can yield up to 10 times the performance when doing random I/O, compared to without NCQ.

For HDDs this is much less an issue.

 

[sweloop64]

The problem with IDE was when two devices were on the same channel(master/slave).
It's like having an elevator that can only go to one floor before having to return to the ground floor, in a two-floor building...
Meaning it was just not possible to use both at once...
The IDE way was to put I/O intense stuff on it's on channel... This is much "like" the SATA way...

 

[sub.mesa]

I think you should call that PATA or Parallel ATA; IDE is not the same as PATA. And yes sharing one channel with two PATA devices can be bad; though usually they aren't accessed at the same time, such as CDROM + HDD which fit perfectly on one channel.

If you want to be academically correct, then you should use PATA instead of 'IDE'. IDE is the design philosophy that the controller is integrated in the HDD itself. The 'controller' on the motherboard is not a controller but a host bridge adapter (HBA). That is the exact opposite of SCSI, and is more like a design philosophy. Therefore, Serial ATA is also IDE; but SCSI is not.