Thanks for your response, mrkrad
You wrote nothing about MEGASCU being useable on a HBA like my LSI 9212 4i4e. Are you retracting that statement? You only showed MSM screenshots.
Is Mobilenvidia correct that MEGASCU can only be used for MegaRaid cards, not HBAs?
You wrote "... 1. The raid card you have has zero cache. It doesn't read nor write cache."
As I wrote in my earlier post, I know the HBA has no ram, so no cache structure can physically be stored on LSI 9212 4i4e PCI-e card
LSI calls this setting Disk
BUT the Samsung 840 Pro has 512 MB RAM. That is the RAM we want to use to store multiple 4K QD=1 Write requests.
When the Samsung 840 Pro is connected to my Dell T110 3gbps sata2 connector, Windows 7 Device Manager allows checking the box called 'Enable Write Caching On The Device"
Since LSI HBA card is not involved at all when the SSD is connected directly to the sata2 motherboard, "DEVICE" as used here by Microsoft MUST MEAN using the Samsung 840Pro 2.5 inch subsystems 512MB RAM (well not all of it).
In spite of the connection being 3gbps sata2, both AS SSD and Anvil report aprox 50 MByte/sec with Microsoft's Enabled write caching on the device (aka writeback).
This shows that if the upstream system will stream multiple 4K Write request to the Samsung 840Pro, Samsung can use its own 512 MB RAM and controller to simultaneously drive multiple channels and cause data to be stored on the physical flash chips in a paralleled overlapped fashion. This is crucial to QD=1, 4K Write performance and is in fact part of what the customer is paying for when buying the Samsung 840 Pro controller and storage subsystem
When two of my Samsung 840 Pros are connected to LSI 9212 4i4e PCI-e card 6gbps sata3 connectors, Windows 7 Pro Device Manager does NOT allow checking the box Microsoft calls 'Enable Write Caching On The Device".
Instead Windows 7 Pro Device Manager says "THIS DEVICE DOES NOT ALLOW ITS WRITE-CACHING SETTING TO BE CHANGED"
MSM refers uses two different terms of art:
SSD Cache Policy (SCP)
Disk Cache Policy (DCP)
SCP is referred to in MSM Physical Tab and again in MSM Logical Tab. Mine shows ENABLED. That makes sense, since my Samsung 840 Pro needs the ability to see more than one 4K Write to be able to drive its multiple overlapped flash channel write capability.
DCP is referenced in MSM Logical Tab, further down the left panel tree the entry is 'Virtual Drive: 0, 474,973 GB, Optimal'. The MSM right panel show that DCP, aka Disk Cache Policy is set to Disable. We expect this, since there is NO RAM available on the LSI PCI-e to be used for LSI card resident cache.
There is a bug in MSM 12.05.03.00 GUI, that would seem to allow Enabling the DCP setting, but upon exiting from MSM and re-launching MSM the DCP setting reverts to Disabled, which is the only value that makes sense for a non-RAM resident HBA, if the setting is referring only to LSI card resident RAM resources available for caching.
I have attached screen snapshots below. Note that MSM Logical Tab shows a Write Policy of 'Write Through' and not 'Write Back', on the Logical node that also shows DCP is Disabled. Probably, the way LSI uses these terms, is that because there is no RAM available to HBA that only Write Through makes sense as far as storing multiple 4K write requests on the PCI-e card. Nevertheless, as directly motherboard connected SSD Microsoft Device Manager show, there is a way for 'WRITE BACK', in the system FUNCTIONAL sense to be used. I don't care if LSI HBA cannot itself implement a oncard LSI PCI-e writeback functionality. WE NEED A WAY TO SEND THESE multiple 4K WRITE REQUESTS ON TO THE DOWNSTREAM SAMSUNG 840PRO, 512 MB RAM without LSI waiting for the Samsung 840 Pro to signal it has completed processing each single 4K write request, which is what I think LSI is doing, and what LSI Technical Support confirmed is now going to be changed.
So mrkad, do you have anyway to do this on any LSI HBA you have actually used??
The answer cannot be use MSM, if the goal is to enable a write policy of writeback. The LSI certified driver needs to be modified in a way that the LSI driver informs Microsoft's Device Manager that Enabling Write Caching On The Device IS POSSIBLE. Not because the DEVICE IS LSI HBA (it has no RAM), but because the downstream
DEVICE subsystem consists of both
LSI HBA + Samsung 840 Pro, and the Samsung 840 Pro does have 512 MB RAM and can accept more than a single write command, as the 50 MByte/sec 4K Write AS SSD and Anvil scores show, when the LSI HBA is out of the equation and Samsung 840 Pro is directly connected to even an Intel 3gbps sata2 motherboard connector.
So I am all ear and eyes, mrkad, it you can show screens that work to enable the ability for multiple 4K Writes to be streamed to the LSI Raid0, two Samsung 840 Pros
. MSM does not provide that.
The goal is quite clear: duplicate the 50MByte/sec AS SSD and Anvil scores, my screen shots show is possible when SSD in connected directly to 3gbps Intel sata2 connectors using same Samsung 840 Pro product.
LSI is crippling the purchased Samsung 840 PRO SSD subsystem as far as 4K, QD=1, writes.
My scores for large sequential transfer are approx. 1GByte/sec for LSI raid0. So that is good.
You claim to have a 4K, QD=1, workaround. But do you have screen shots that work for a LSI HBA card?
https://www.dropbox.com/s/tlc3c2xx5qof6ck/Physcial Tab-SSD Disk Cache Setting is Enabled.jpg
https://www.dropbox.com/s/vp7mnu7em... node SAS9212 4i4e bus2 dev 0-SCP Enabled.jpg
https://www.dropbox.com/s/vp1d19r8m... Diable and Write Policy is Write Through.jpg
https://www.dropbox.com/s/817hyu7qt...ALLOW Write-Caching Setting To Be Changed.jpg
https://www.dropbox.com/s/f8w0anmxu...ALLOWS ENABLE Write-Caching ON THE DEVICE.jpg
https://www.dropbox.com/s/n8tfp4ccm...led or Enabled-always reverts to Disabled.jpg
Anyone else able to solve this with tools that work?
mrkad, I did not see your last post, until I posted this large post.
You wrote>"... Any 'Mega' utility is for MegaRAID cards 9260/65/70 etc etc". That corrects your previous recommendations to use MegaSCU for LSI HBA cards
You also wrote>"... HBA's need SAS2FLASH (sas2flsh DOS) or LSIUTIL ... Neither of which can enable drive cache ... The only way is via MSM"
Yes, I have successfully used SA2* to flash my LSI 9212 4i4e to P16 firmware.
As I wrote MSM will NOT work to make any changes. MSM GUI offers the apparent option to change Disk Cache Policy from Disable to Enable, but this reverts to Disabled (which is the only setting that makes sense for a HBA, as LSI uses these terms).
I think Mobilenvidia mentioned somewhere that he uses the Microsoft and NOT LSI driver? Anyone know how to do that? If possible, would this then allow Microsoft Device Manager to allow checking its Enable Write Caching box, since LSI driver would be out of the equation. Does it makes sense to use only Microsoft driver (which one?) to successfully write to a LSI IR mode raid0 volume?