SSD Maintenance

Trim on SSD Drives

this a generalization of most ssd drives

What trim does is mark these blocks/files etc and make it simpler for the inbuilt GC ( garbage collection ) to recognize the blocks that are available for further use, on some controller’s this will not necessarily happen immediately, it depends on whether the controller as been designed for “idle” use, “on the fly” use or “stand by use”, GC/Trim can be brought into use in many different ways, having the computer sitting with the bios open, having the computer idling at log in, placing the computer in stand by mode, deleting files or just simple idling the computer overnight. It’s a matter of finding out how the controller in your particular ssd handles the garbage collection. You will find the most efficient way is by experimentation or by other members passing on there particular way of doing it.

Low level formatting used on conventional HDD drives writes mainly 0’s to every cell on a SSD drive, it’s the opposite to how flash memory actually works, if you low level format with Win7 or any software that writes 0’s or 0’s and 1’s to the individual cells, you are not necessarily cleaning the ssd drive completely, ( hence the need for secure erase software ), you can actually make the performance worse.

If you use software designed for writing 1’s to each cell, like you would if it was designed for ssd drives, this will “clean” the drive and is a good thing to do if you are selling the drive, or as a last resort, if you are having problems with your ssd drive. The downside of using this type of erasure, is that it not only takes a long time it uses high write amplification and if used regularly can reduce the flash cells life expectancy considerably, these type’s of deletions bypass most controllers durawrite capabilities ( the way controllers extend the life expectancy of the ssd’s individual MLC cells ), Durawrite ( Sandforce ), other controllers have this technology in some form or other, it increases MLC life expectancy by between 5 and up to 30 times depending on the design of the controller.

TRIM occurs when the ssd clears blocks of invalid data. When you delete a file, the operating system will only mark the area of the file as free in order to trick the system into believing the space is available. Invalid data is still present in that location. Its like ripping out a Table of Contents from a book. Without this, one would not know what, if anything, is contained on the following pages. TRIM follows the process of marking the area as free by clearing the invalid data from the drive. Without this, the process of reading, identifying invalid data, deleting or moving and clearing the block before writing can actually result in performance 4 times slower than it would have normally been as a new drive.

In recently speaking with Kent Smith, Sr. Director of Product Marketing for SandForce, he identified that there are many variables outside of the hardware that are responsible for users not seeing the benefits of TRIM, the first of which are drivers at the OS level which have to be working optimally in order for TRIM to function correctly.

Another example occurred with early Windows 7 users testing their newly installed drives and not seeing the benefits of TRIM. Examination of these complaints revealed that users would have originally made the Windows 7 installation on hardware that did not support TRIM and then cloned to the SSD to which TRIM was supported but would not work because of the original configuration settings.

The same could be said of cloning an OS that originally had AHCI turned off followed by a clone to the SSD where TRIM was not being passed, simply because AHCI has to activated for TRIM to function.

Filling a drive to capacity will hinder TRIM and GC ability which will result in performance degradation. Many drives will start to display performance changes once filled to 70% capacity.

Now, I want to be clear, a sufficiently clever GC on a drive that has enough reserved space might be able to do very well on its own, but ultimately what TRIM does is give a drive GC algorithm better information to work with, which of course makes the GC more effective.

http://www.devwhy.com/blog/2009/8/4/from-write-down-to-the-flash-chips.html

Before you clone, install TRIM Enabler

And after you clone, run Disk Utility's REPAIR DISK on the SSD -- just to be on the safest side.

http://www.macupdate.com/app/mac/37852/trim-enabler

Trim is must-have feature for most Solid State Drives. It not only increases data writing speeds, but it increases the lifetime of the SSD itself. With Trim Enabler, you can bring that feature to Mac OSX. It’s as easy as flipping a switch.

Trim Enabler can also analyze your drive and show information about it’s health and show lifetime statistics.

http://www.groths.org/trim-enabler/

Looking for input from you and others. I dropped out of tipping 😉

Adding 1TB of SATA3 SSD with Apricorn and Highpoint RAID to my 2009 MP

http://forums.macrumors.com/showthread.php?t=1504491

Real world experiences with Sonnet Tempo Pro and 2 Samsung 840 Pro SSDs

http://forums.macrumors.com/showthread.php?t=1605500

Samsung has new firmware for the 840 120GB - use Samsung Magician (v. 4.1) on Windows to get it.

Samsung SSD 840 EVO Review: 120GB, 250GB, 500GB, 750GB & 1TB Models Tested

http://www.anandtech.com/show/7173/samsung-ssd-840-evo-review-120gb-250gb-500gb- 750gb-1tb-models-tested

9 months after the release of the Samsung SSD 840 and we have its first successor: the 840 EVO.

The non-Pro version of the 840 was the first large scale consumer SSD made with 3-bit-per-cell MLC NAND, more commonly known as TLC (triple-level-cell) NAND. Companies had toyed with the idea of going TLC well before the 840's release but were usually stopped either by economic or endurance realities. The 840 changed all of that. Although it didn't come with tremendous cost savings initially, over time the Samsung SSD 840 proved to be one of the better values on the market - you'd just have to get over the worry of wearing out TLC NAND.

Despite having a far more limited lifespan compared to its 2bpc MLC brethren, the TLC NAND Samsung used in its 840 turned out to be quite reliable. Even our own aggressive estimates pegged typical client write endurance on the 840 at more than 11 years for the 128GB model.

The cores now run at 400MHz compared to 300MHz previously, which helps enable some of the higher performance on the EVO.

The MEX controller also sees an update to SATA 3.1, something we first saw with SanDisk's Extreme II. SATA 3.1 brings a number of features, one of the most interesting being support for queued TRIM commands.

TurboWrite does a good job of blurring the lines between MLC and TLC performance, while Samsung's RAPID DRAM cache offers adventurous users a way of getting a taste of high-end PCIe SSD performance out of an affordable TLC SATA drive.

The 1TB version is exciting because it offers a competitive price with the 960GB M500 but with better performance.

Samsung expects the 840 EVO to be available in the channel at the beginning of August.

There is an update on the Samsung site to firmware DXT08B0Q.

They even provide a Mac version with instructions here:

I posted above already about SATA 3.1 Which incorporates how NCQ and TRIM are being handled.

TRIM SSD and GC

The SATA 3.1 specifications Queued Trim Command - allows SATA SSDs to execute Trim without impacting normal operation...

http://www.sata-io.org/technology/6Gbdetails.asp

Now everyone may not have a new enough SSD and who knows what Mac OS they use and to me whether that has any interference or not.

If you have a list of which SSD incorporates or not TRIM in the controller and firwmare that would be a positive contribution. Yours was not.