- M.2 Type 2280
- 256GB
- SATA 6Gb/s
WORKS buts needs Adjustments
09/09/2014
This review is from: Crucial M550 M.2 Type 2280 256GB SATA 6Gb/s MLC Internal Solid State Drive (SSD) CT256M550SSD4
Pros:
This new drive form factor is an in expensive alternative to a traditional SSD and is very fast
Cons:
There is a serious Driver issue that requires a fix outlined below.
After trying to get Gigabyte support to resolve, I spoke with support at Crucial and found they really had no clue as to why this was happening. During the discussion, they provided a few links to suggest fixes ranging from adjusting the HIPM & DIPM to tweaking the registry.
Working through these I found what the ROOT CAUSE is and how to fix the problem. Here is a summary of the cause and how to fix.
The real issue is the Intel SATA Chipset requires and iaStor drivers. The iaStor drivers were changed a few revs back to include Load Protection Modules (LPM) where the drivers try to manage faults in low loads at the Power Supply Unit (PSU) level. This change introduced a flaw in how the PSU handles power to SSD and Spindle drives to prevent too low of power being fed to these devices. The change did not take into account the M.2 format.
A Traditional SSD has a slow bleed capacitor to maintain its operation and the normal mechanical drive can simply shut down without issue. The M.2 format does not appear to have the SSD slow bleed capacitor and therein is the problem.
The iaStor driver’s simply cut power at the PSU under LPM, which causes the M.2 format drive to simply disappear in BIOS, thus the need to power down the PSU to rediscover the M.2 drive. This may be Crucial or in my case Gigabyte issue but I suspect it’s the iaStor driver only since this is happening across a wide range of motherboards and may be happening with other M.2 manufacturers as well.
Let’s hope the manufacturers get this information and adjust as needed so we don’t have to perform manual adjustments going forward.
Overall Review:
THE FIX:
Through trial and error, the issue is really very simple. The LPM in the iaStor drivers must be turned off since it is on by default. The registry entries for this don't exist for the LPM as installed by the driver. Manual registry entries are needed to turn off LPM for the specific iaStor ports supporting the M.2 drive are required to fix this problem. You won’t want to shut off all LPM ports since they are needed for the other drive form factors to function properly
Each motherboard or iaStor driver may setup its own registry entries. The default single or fresh install should be [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\iaStor\Parameters]. However, my current installation has three variants (same location) iaStorA, iaStorF and iaStorV. Locate the one that includes the ‘Device’ Key and use the path in building your registry dword strings shown below replacing the "iaStor" as needed. Remember only include the ports associated with the M.2 drive, if you want to include them and have the LPM mode enable, change the dword value to “dword:00000001”.
I copied and pasted only Port 4 & 5 in to a text file named ‘LPM.reg’, for my Gigabyte MB since those are the ports supporting the M.2 drive. Once you have the file created, double click on it to load the registry entries via RegEdit. If the path is good, you will see a message the keys were successfully loaded. If the path is not valid, an error message will ask if you what to create them – say no and correct the path in the file.
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\iaStor\Parameters\Port0]
"LPM"=dword:00000000
"LPMDSTATE"=dword:00000000
"DIPM"=dword:00000000
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\iaStor\Parameters\Port1]
"LPM"=dword:00000000
"LPMDSTATE"=dword:00000000
"DIPM"=dword:00000000
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\iaStor\Parameters\Port2]
"LPM"=dword:00000000
"LPMDSTATE"=dword:00000000
"DIPM"=dword:00000000
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\iaStor\Parameters\Port3]
"LPM"=dword:00000000
"LPMDSTATE"=dword:00000000
"DIPM"=dword:00000000
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\iaStor\Parameters\Port4]
"LPM"=dword:00000000
"LPMDSTATE"=dword:00000000
"DIPM"=dword:00000000
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\iaStor\Parameters\Port5]
"LPM"=dword:00000000
"LPMDSTATE"=dword:00000000
"DIPM"=dword:00000000
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- Daniel W.
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