Possible cause (and fix hopefully!) for corruption on nForce4 SATA drives (and request for info!)

[tokyovigilante]

Hi guys,

 

[Disclaimer: I am not a computer hardware designer or builder, all the information/rambling below is based on my own reading and interpretation of various sites and forum posts. I accept no responsibility for its accuracy, or any ill that comes to you or your hardware or data while applying the information below. Back up, try on non-mission-critical hardware, and for the love of god, don't do anything if you're not sure of the ramifications!! That said, on with the show!)

 

I stumbled across some interesting things while trying to shoehorn JaS' DVD onto my AMD64 system (A8N-SLI, Athlon64 3800+ X2, Hitachi T7K250 SATA). Installing through VMWare worked onto a real partition worked until I rebooted into the system, and had all sorts of kernel panics. I'm downloading Myzar's 10.4.5 at the moment, and will see how that runs, but I digress...

 

I was installing through VMWare because a native install failed at random points in the file copy process, and running disk utility on the partition after reboot showed numerous corrupt files on the partition. This didn't bode well for my install, so I went off in search of the answer, and found something very interesting.

 

The SATA II 3gbps spec includes a new (for hard drives anyway) technology called Spread Spectrum Clock (SSC). As drives get bigger and faster, the electromagnetic interference (EMI) they create increases, to the point where multiple SATA drives in a system can break FCC (for you poor souls in the US regulations. To fix this, the HD manufacturers stole SSC from the radio industry. Basically it shifts the frequencies that EMI is emitted from your HD, so that the spectrum is spread, and while the total emission is the same, the emission on any one frequency is lower. Sounds cool right?

 

Well it would be if it hasn't caused all sorts of issues for our Windows-running buddies, and by issues I mean data corruption just like I and others on this forum with nForce4 chipsets and SATA drives. http://forums.nvidia.com/lofiversion/index...?t8171-300.html

http://forums.nvidia.com/lofiversion/index...?t8171-250.html

 

I've had a look through and tried to separate the wheat from the chaff. One of the main things I found was the issue of SSC. It seems not all hardware supports this chipset option, and when it is enabled without hardware support, it causes data corruption.

 

This has also been seen on the seagate drives in some Intel iMacs (today's (21/4) news on xlr8yrmac.com)

 

Seagate and Hitachi have options to disable it on the drives, and some motherboards (DF1 Lanparty etc) have the option to disable it. However on systems that do not support it, (eg most nForce4 boards) don't, so you need a utility from the manufacturer of your hard drive. It doesnt add any functionality to your drive, just makes it less likely to produce EMI. You generally shouldnt need this option unless EMI is an issue for you.

 

What is particularly interesting is that AFAICT, VIA (whose driver we poor nForce4 saps are using for SATA) does not seem to support SSC, and if the system doesnt know the drive is using it, then its corruption galore!

 

I'm going to get this tonight, disable SSC and try and reinstall OS X. I'll post my success/failure up.

 

In the meantime, if anyone who has had corruption could let me know the specifics of their drive and motherboard, and especially whether it is a SATA-I (1.5gbps) or SATA-II (3.0gbps), as I think only SATA-II drives have SSC.

 

Whew. Wish me luck!

[tokyovigilante]

Awesome. I've used Hitachi's ftool utility to switch my driv from SATA-I to SATA-II (1.5->3.0gbps) and disable SSC, and was able to complete the installation natively. Still having kernel panics when booting, even with the PPF slipstreamed in, so I'm going to get Myzar's 10.4.4/10.4.5 DVD and have a play with that. Doesn't look like much AMD dual core success on these forums, despite JaS' best efforts.

 

Long story short, disabling SSC seems to have fixed the nForce4 corruption issue, at least for me. Good luck with your installs!

[macprodan]

So your saying Disabling SATA Spread Spectrum in the Bios should sort this. Im pretty sure i Have this Disabled already, but still Get Freezes when have 1 or 2 SATA Drives connected.

 

I Have The OS on an ATA133 Drive at the Mo, would love to use my SATA's for the OS's and the ATA for DATA but until i have 100% stability i am not gonna risk it.

 

Ill chk now to make sure SATA Spread Spectrum is Disabled in the BIOS.

[thunder.scripts]

I have it disabled and it works for a few minutes, then freezes

 

HD SATA I Western Digital 80 gb

[tokyovigilante]

I think the real issue is that the implementation is so patchy between chipset and HD manufacturers that you may need to disable it on the drive as well as the motherboard, as some drives ship with it on, others off, and some SATA-II drives ship in SATA-I mode for compatibility.

 

Disabling it directly and switching to SATA-II on my Deskstar using Hitachi's uility was the difference between my install succeeding and failing. I haven't managed to get the install to boot yet due to various kernel panics, but Myzar's ISO should be done in 6hrs or so, and I'll get that on and see how I go.

 

@thunder.scripts: If you boot into yr DVD and run disk utility, do you see file corruption?

[thunder.scripts]

JaS DVD doesn't see my hd, I had to install OS X directly into it using VMWare

[tokyovigilante]

JaS DVD doesn't see my hd, I had to install OS X directly into it using VMWare

That's not so much of an issue, I can install through VMWare too. This bypasses OS X's SATA driver, emulating a dummy IDE driver, so there is no risk of corruption. The issue most people are facing is that the VIA ATA driver being used for nForce4 seems to be corrupting data. Hopefully the above will help some people, it seems to have helped me.

 

As to your issue specifically, if you make a AF partition with diskpart in Windows, can your DVD then see the disk? Have you patched your JaS DVD with the PPF? I installed successfully to a SATA drive with JaS' DVD but then get kernel panics on reboot into the system, I think this may have something to do with AMD dual core support. I'm trying Myzar's DVD now, we'll see how that fares.

[jape]

I don't really think SSC is the cause here.

 

Having SSC disabled on the MoBO while enabled on the HDD would cause not "random" data corruption, but rather massive corruption up to the point the partition table could not be succesfully read. So I guess disabling SSC is a placebo effect, or maybe there is something behind that is hiding the real reason for failure.

[thunder.scripts]

No, the install dvd never sees the partition :S

 

However, I can boot natively using the SATA disk once it was installed. The problem is that it freezes a few minutes after using it.

[jape]

However, I can boot natively using the SATA disk once it was installed. The problem is that it freezes a few minutes after using it.

This is my problem, too. Notice how you can make it freeze it later or sooner by i.e. playing iTunes, connecting USB hardware, messing with Rosetta, etc. Don't know if it's related to disk activity, but it doesn't seem too, as moving files around it doesn't hang. I think (as I said on other posts) that every hw access (usually pci) can trigger the freeze.

 

Also sometimes, the system seems to "remount" the root partition read only (possibily due to i/o error). This is disastrous to the system. I suspect that it freezes while it does try to "remount" the root partition. Sometimes it succeds (every app that tries to write to disk then fails with "Unknown error -50", even basic utils like "touch"), sometimes it doesn't -- the system has no root partition and instantly freezes.