SATA and SAS Confusion

[Fastline]

So, i had some SAS SSD which i got from a friend and i used a Cable Deconn Cable to test the drives. What surprises me is that the SAS interface has extra pins on it but the cable does not have, but still the SAS drive works. My question is, what that extra pin does, if the drive works without those extra pins on the cable.

As you can see, the cable does not have those extra pins for the connectivity

Are those extra pins for carrying disk information like the SGPIO signals for the blackplane? I think, that’s the case. Cause, no disk information is available in HD Sentinel.

[Arwen]

Simple.

SAS devices have 2 ports, which can allow 2 different paths to the same disk. (Including 2 different hosts…) Normal SATA has 1 port, which SAS copied.

You can not use both SAS ports on a storage device to get double device to host transfer speed. SAS does not work that way. So what you have is probably just fine for non-Enterprise work.

[Fastline]

I see. So, that means, the other pins are not required for SAS operation?

Also, why the disk information is missing?

[Stux]

If you notice there are seven pins on the left side of the plug. That’s effectively a sata plug.

There are seven pins on the middle part two. Effectively a second sata plug. Which is not needed to use the drive.

And then all the other pins are power.

I believe enclosure services etc are carried inside the SAS protocol, rather than on actual pins.

[Fastline]

@Stux

I believe enclosure services etc are carried inside the SAS protocol, rather than on actual pins.

Yes, i think the same. Probably, that’s why the Disk information is not visible.

[Arwen]

@Fastline

no disk information is available in HD Sentinel.

@Fastline

Also, why the disk information is missing?

I don’t know what HD Sentinel is, but from what you said, sounds like a piece of software. Searching the web, it appears HD Sentinel supports SAS so I don’t know why it would not list disk information.

However, SAS is totally different command structure compared to SATA. So it is possible you have run across a bug in HD Sentinel for that device.

• SATA is based on the old PATA, which is a more formal name for IDE, (Integrated Drive Electronics)
• SAS is based on SCSI, (Small Computer System Interface), which used to use parallel cabling similar to PATA / IDE, but not compatible. SCSI was available years before IDE.

Further, SATA’s serial protocol came out first, so SAS development team decided to make some compatibility between the 2 standards. BUT, only one way, (all SAS controllers support both SAS & SATA storage, but the opposite is not true).

[Stux]

@Arwen

PATA, which is a more formal name for IDE

PATA is actually a retronym, it was ATA

AT Attachment (as in IBM PC/AT) and it only made sense to describe it as Parallel ATA once there was a Serial ATA version.

And SAS is Serial Attached SCSI

Story time:

I enjoy using SCSI again… used all the old variants… but nothing was as chunky as its spiritual predecessor…

Which explains where the word “small” comes from in SCSI.

[joeschmuck]

There is high density SCSI connectors which are absolutely no fun to connect. It is very easy to bend a tiny pin. I used to mate and de-mate these connectors every week, sometimes several times a week just to swap out hard drives with unique software on them so the software developers could play.

No disk information? Please explain or maybe a screen shot.

The drive not being recognized is not the same as SMART data not being available.