11-30-2012 01:54 PM - edited 11-30-2012 02:00 PM
I just replaced the 500gb HDD/32gb SSD stock setup with a Samsung 128 SSD and a Crucial 64gb mSATA. No issues with the switch (didn't even have to break the RAID manually - it was automatically broken when both components were replaced), and IRST is reporting that both new components are healthy. However, the Samsung SSD software is reporting that the 128 is running in non-AHCI mode, and there's no way to change mode in the BIOS. Speed is not a concern - the Samsung software is reporting over 520mb/s read, 300+mb/s write - but TRIM/garbage collection commands are. fsutil is reporting that TRIM is active in the OS, and CrystalDiskInfo indicates that both drives have TRIM active - but the HKLM registry entry for msahci was set AHCI off (I set it to "on" - probably an unwise idea without also being able to set the BIOS - but Samsung still reports AHCI off). Are TRIM/garbage collection commands being passed to the SSDs? The Samsung software has a manual TRIM command ("Drive Optimization") that I can run as needed, but the Crucial mSATA has no such software. As I'm using the Crucial for user files (as well as the iRST hibernation partition), I really don't want the thing slowing to a crawl and failing due to a lack of TRIM.
Is there any way to determine if TRIM commands are being passed to the mSATA?
11-30-2012 02:26 PM
Garbage collection on the newer SSDs is part of the device's firmware. The garbage process kicks in when the PC becomes idle for a while. For systems where trim is not available then garbage collection is the substitute.
Your Samsung appears to be running just fine.
11-30-2012 06:34 PM - edited 11-30-2012 06:49 PM
Thanks for the response, Dave.
My understanding (as imperfect as it is) is that Trim is required to tell the SSD what files have been deleted; without it, Garbage Collection can and does move deleted files, as the SSD doesn't "know" the file's been deleted. While I'm not going to be stressing the Crucial by any means (I'm a writer, not a video editor), I worry about write amplification becomming an issue.
Think I'll download CrystalDiskMark and benchmark the Crucial (and why that doesn't come with a software suite similar to the Samsung is beyond me).
[quote]...Your Samsung appears to be running just fine.[/quote]
Thanks. I was surprised at the performance, especially without AHCI running.
11-30-2012 09:13 PM - edited 11-30-2012 09:24 PM
Thanks for the response. I am sure that there are plenty of high performance SSD RAID users that don't benefit from trim. While trim is being asked for in RAID mode, it appears to be a ghost right now. I know Intel is working on trim support for RAID. We also have XP users that are using SSDs. Oh well, the life of the SSD is just getting a bit shorter.
The trim operation from my understanding just tells the drive earlier when to purge data. The newer SSDs do a much better job with garbage collection than older drives. Even still, I would prefer to have my cake (trim) and eat it at the same time.
11-30-2012 09:36 PM
Valid point. As I'm not a heavy disk user, this is rather academic - I seriously doubt I'll wear out either drive before wearing out the laptop - but it's one of those "last 1%" things that's irking me.
I seem to remember something about this version of Intel's RST passing Trim commands thru the RAID controller, but I'll be darned if I can find it again; I'm hoping someone here can chime in and confirm/deny.
I also wish HP hadn't restricted the BIOS so completely. I've been searching online for a while, and there is apparently no way to activate AHCI - which would render this entire conversation moot, as AHCI passes Trim commands. Grrrr...
Thanks again, Dave. Your comments are appreciated.
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