Sony VAIO SVT13112FXS ultrabook blue screen caused by iastor.sys

My beloved Sony VAIO ultrabook laptop, model SVT13112FXS (SVT131A11L) is crashing every 10 minutes or so, even if it is idle, with a blue screen (BSOD).   Blue screen says the problem is related to iastor.sys .    This machine runs Windows 7.

This machine has a hard drive and a solid state cache drive and iastor.sys is the intel RAID driver that allows the computer to use two drives as if it is a single drive, do fast caching, etc.



This all started after I left the machine behind at home on an international trip.   Normally it is my travelling companion, but this time I didn't want the hassle of taking two laptops through security.  I left it at home, unplugged, and probably in sleep mode.  The battery drained completely and when I returned it was lifeless.   I plugged it in and it complained that windows wasn't shut down properly but otherwise initially everything seemed OK.  After 10 minutes of use, the blue screens started.

In the end the fix was to replace the SSD cache drive.   This is a hardware problem, not a software problem.  Not a difficult repair.  Involved unscrewing the back cover and pulling out one module and buying a replacement off eBay for $35. A little fooling around with the BIOS and Intel Rapid Store Software and all is good.

Here is the whole debug trail...

Possible causes

• iastor.sys (Located in C:\windows\system32\drivers\iastor.sys) is corrupt
• A hardware problem with one of the disks
• Malware (this is a favorite vulnerability among hackers)
• Virus scanner killing the machine on purpose when it finds something it can't fix

Here is what I tried

• System restore to older time.  Didn't solve the problem, and I regressed to before I started having the issue.  
• Ran chkdsk (right click on the drive, tools, check disk) and schedule a scan, reboot.  chkdsk fails in the middle with the BSOD and it reboots endlessly scanning and crashing.
• I removed the hard drive and put it in another machine and ran chkdsk.  Completed and found no errors.  But it back in the laptop and still crashes
• Ran sfc /SCANNOW which completes, and says no errors.   Still crashes.
• Downloaded and ran tdsskill.exe from Kaspersky.  This is supposed to catch malware that poses as iastor.sys.   It ran and found no problems.
• Ignore all the lies about rkill, malwarebytes, etc.  Those programs have never worked for me and you end up getting more malware on your machine.
• Full virus scan of the disk from another machine.  It's clean
• Msconfig, went through and stopped every process from the start menu that I didn't recognize.   Didn't help
• Tried to replace the iastor.sys files by hand.  My other computers don't have this file to copy from since they don't have a RAID.  
• Renamed the iastor.sys to iastor.sys.X.  Now the machine won't load windows.  It wants to do startup repair but eventually BSOD's into the same screen.  Dead end. 
• Put the drive back in another machine and restored the iastore.sys and iastorV.sys files from a previous version
• Went to https://downloadcenter.intel.com/Detail_Desc.aspx?DwnldID=17882 to download iastor.sys from Intel.  None of the packages recent packages contained a 64 bit iastor.sys, just various versions like iastorV.sys, iastorF.sys.  WTF?
• Downloaded IATA89CD.exe from above site and ran.  This is supposed to contain the Intel Matrix Storage Manager.  It is dated 2009 it seems, don't know how this could be the right file.   A window pops up and says the computer has version 11.0.0.1032 and the installer wants to overwrite with 8.9.0.1023.  Seems wrong.  Plowing ahead.  It installs OK and reboots.
• Won't start windows anymore.  Bombs  Lovely.  Startup repair wants to run and restore the machine to an earlier point.  Fail.  Didn't let it regress but startup repair failed.
• Rebooted and tried startup repair again. Fail.  However the machine did not load windows, and I got another BSOD for iastor.sys.   Now i'm stuck in a loop of BSOD and startup repair.  
• Eventually it lets me do a system restore and back out the changes to an earlier time.  Finally it boots to windows but I'm back where I started with repeated BSODs.
• May have downloaded the wrong thing.  Searched again and found this:  https://downloadcenter.intel.com/Detail_Desc.aspx?agr=Y&ProdId=2101&DwnldID=23060&keyword=intel+rapid+Storage+Technology+(Intel+RST)&lang=eng
• Installed it successfully.  Restarted the computer.  windows boots.  Now I have multiple versions of iastor.  iastorF.sys, iastorV.sys, iastorA.sys, as well as iastor.sys.   Letting the computer sit for a while to see what happens.  Boom BSOD.  Fail.
• This must be a hardware problem since I've done everything conceivable to fix iastor.sys
•  I want to try disabling the cache drive in the BIOS.  Drive may be malfunctioning.  F2 at the black sony screen is the way to get to BIOS:  https://us.en.kb.sony.com/app/answers/detail/a_id/35240.   Can't find any way to access the disk drives in the BIOS!  WTF?  BIOS has been nerfed.
• I need to pull the cache drive.  Went hunting for it.  Unscrewed the three large screws on the battery and removed the battery.  THree screws to remove the hard drive cover.  Unscrewed the hard drive too, four more screws. (did this previously because I had put it in another machine).  Opened up the back panel by removing all the small black screws around the outside edges on the bottom and two silver ones in the battery compartment.  The bottom cover pops off with a little prying.

VAIO with the battery and hard drive removed

VAIO with the back cover removed.  The PCIe SSD cache drive is the small green circuit board on the top edge towards the left.

• Found the SSD cache drive.  The little module at the top edge near the WLAN module.  Removed one screw and pulled it out.  It is about 2.5 inches by 1.5 inches with two samsung chips on it.

Removed Samsung SSD

SSD flipped over, the part number is on the bottom side

• reBooted and I get a disk drive BIOS menu now!  It noticed something changed.  
• First attempt I tried to just bypass the bios screen, I get "operating system not found"  Power off and restart.
• Next I try <Ctrl I> when it asked me and it tells me the cache volume is not present.  Do I want to disable it?  Bingo.  Answer yes.
• Computer boots to windows.  A lot slower now. too bad.   But it works!
• If this fixes the problem I will have to decide if I'm going to buy a replacement cache drive, live with the slower boot, or buy a single SSD drive and figure out how to reload windows from scratch.
• So far so good.  System is stable.  It is no longer BSOD every few minutes.   Problem is I don't really know if the problem is the cache drive hardware or the software that talks to it.   Since I removed the drive, both are gone now.   Seems like I fully explored the software corruption angle, but it is impossible to be sure it wasn't a related file that expressed itself as an iastor.sys BSOD.
• Found a used replacement 32GB drive on ebay, they are pulls from used equipment.  Prices vary from $29 to $49 for a new one.  Many are shipped from the far east.  
• Found some refurbs from US sellers
• http://www.ebay.com/itm/151116902504
• 
• Pulled the trigger for $35.  I figured it is worth the risk.  If the problem returns, then it isn't the hard drive and I can resell the part on eBay.
• I will update the post when the new part comes.  Meanwhile I'm back in business without the cache drive.  Computer works normally, it is just slower to boot and hibernate.  24 hours plus and still going without a BSOD.
• New part came in the mail.  Looks identical to the old one.
• Opened the laptop back up again
• Plugged in the replacement drive.
• Rebooted.  Now it noticed something was different and the disk BIOS menu came up, 
• 
• and I pressed Ctrl I to configure as i did before.
• 
• I tried options 1 and 5 and both said Error.  "Not enough available space to create a volume".  I eventually I just exited and it booted normally.  I'm not sure if the caching is going to automatically turn back on.
• Hard to tell if cache is working
• Rebooted again and the BIOS menu came up again.  Dang.  It still says "Disabled" next to the cache drive.  Can't find out how to enable it.  When I disabled it before it was obvious, but I didn't take a picture.
• Disk shows up in windows under computer management but no options to enable it are obvious 
• Re-installed the windows RAID driver software I downloaded above   https://downloadcenter.intel.com/Detail_Desc.aspx?agr=Y&ProdId=2101&DwnldID=23060&keyword=intel+rapid+Storage+Technology+(Intel+RST)&lang=eng
• From Windows:  Start->All Programs -> "Intel Rapid Storage Technology"  
• Status "Your system is functioning normally" and I see the a 30GB RAID array with 11 and 19GB sections. 
• A message at the bottom says "Acceleration using solid state drives: Disabled" and please reconnect the the accelerated disk or volume..
• Indicates that the drive is no longer accessible. 
• In the manage menus 
• Turned off and disabled the SSD cache, reset the drive
• Tried to re-enable accleration, it says I must reboot
• rebooted
• Reentered Intel Rapid Storage Technology-> Performance, and turned on Acceleration!   
• Now it works.   W00t!
• It appears I had to clear out all the old data on the refurb drive and re-associate it.   I think it was looking for the old drive ID.  Looks like I'm back in business.  
• Soaking to see if it crashes.  So far so good.  24 hours + and no BSOD.
• Victory declared!