This message is from the T13 list server.
Wolford, Jeff wrote:
This message is from the T13 list server.
There is NO conspiracy on PIO CRCs.... It is just as simple as this:
1) SATA PIO transfers have a capability that PATA PIO transfers do not,
they have a CRC that is part of the transfer, and
2) so CRC errors can be detected (notice the word detected)
3) to take advantage of this "improvement" a reporting mechanism was
needed, thus the proposal of using iCRC on PIO transfers.
Thanks Jeff...
However, I still don't see an explaination for why this error reporting
(using ICRC) was not in SATA 1.x or in ATA/ATAPI-7. I understand that
SATA has CRC on all data packets (FIS) transferred on the SATA
interface. If using ICRC to report SATA CRC errors is now needed why was
it not needed 2 years ago? I'm still waiting for someone to explain how
these SATA CRC errors are reported by the millions of SATA devices that
have been shipped that do not support this new use of ICRC for PIO
transfer commands, and for someone to explain what risk to data
integrity when using devices that do not implement this new use of ICRC
use during PIO transfer commands. Someone in SATAIO land must understand
this problem/question/issue and understand the serious question this
raises concerning the data integrity of the SATA interface devices
shipped during the last 2 years?
It was NOT that SATA needed it, it was that SATA could improve over
PATA.
Yes, SATA can improve over PATA. But why did we have to wait two years
to get a documented method for reporting SATA CRC errors? Surely someone
in SATAIO land can answer this question?
Re: Host compatibility
Yes, you will need drivers that know about this new feature to take
advantage of it.
You are saying that SATA is not compatible with PATA and that anyone
using SATA devices via a SATA host that emulates PATA is using devices
that place their data at serious risk of corruption. Of course you are
not the first person to say this. So why have not tell people what the
risk is? What is the error rate (many people can see that it is higher
than native PATA)?
The fact that I have asked these questions so many times with no answer
tells me that one of two things is going on... Either a) there really
isn't anyone in SATAIO land that understands the basic idea of data
integrity (I can't really believe this), or b) there is some reason
SATAIO does not want to reveal the problems of error reporting in SATA
(and I sure hope this isn't true). But SATAIO needs to answer these
questions so that everyone can understand the true nature of SATA
reliability. Just saying SATA is better than PATA doesn't make it so.
Hale
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++ Hale Landis ++ [EMAIL PROTECTED] ++
