List of SSDs that support ATA TRIM
<h3>What is ATA TRIM?</h3>
An SSD's total size is composed of thousands of smaller units called "blocks," which average about 512k these days. SSDs deliberately try to spread written data across all of these blocks so as not to prematurely wear out the memory chips, which can only accept a limited number of writes. This technique is called wear leveling. Over time, wear leveling guarantees that every block on the SSD will receive a write of data at one time or another.
When this is combined with Windows' delete mechanism, which only marks space as free rather than physically removing the data, an SSD is guaranteed to get gummed up with a hodgepodge of deleted and undeleted files. When the SSD's physical cells are full, regardless of the displayed free capacity, the drive must perform a complicated routine called the read/erase/modify/write cycle to store new data.
An REMW cycle forces an SSD to scan its blocks for deleted but unpurged files, copy active data to cache, purge the deleted files, append the new data to the data in cache, and then write the cache back to the new free space. This is called write amplification, and in serious cases, it can force an SSD to shuffle up to 20GB of data just to write 1GB of new information. This causes significant performance issues for SSDs.
The solution to this problem is to let SSDs physically erase files the moment they are deleted in the OS, and that is precisely what the TRIM command does. Windows 7 and Windows Server 2008 R2 are the only Microsoft OSes that support it, and the feature cannot be used without support from both the drive's controller and firmware.
An SSD's total size is composed of thousands of smaller units called "blocks," which average about 512k these days. SSDs deliberately try to spread written data across all of these blocks so as not to prematurely wear out the memory chips, which can only accept a limited number of writes. This technique is called wear leveling. Over time, wear leveling guarantees that every block on the SSD will receive a write of data at one time or another.
When this is combined with Windows' delete mechanism, which only marks space as free rather than physically removing the data, an SSD is guaranteed to get gummed up with a hodgepodge of deleted and undeleted files. When the SSD's physical cells are full, regardless of the displayed free capacity, the drive must perform a complicated routine called the read/erase/modify/write cycle to store new data.
An REMW cycle forces an SSD to scan its blocks for deleted but unpurged files, copy active data to cache, purge the deleted files, append the new data to the data in cache, and then write the cache back to the new free space. This is called write amplification, and in serious cases, it can force an SSD to shuffle up to 20GB of data just to write 1GB of new information. This causes significant performance issues for SSDs.
The solution to this problem is to let SSDs physically erase files the moment they are deleted in the OS, and that is precisely what the TRIM command does. Windows 7 and Windows Server 2008 R2 are the only Microsoft OSes that support it, and the feature cannot be used without support from both the drive's controller and firmware.
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If these companies offered and incentive such as a rebate on another after the drive has reached its life expectancy would be nice.
If NAND cells the drive wants to write to are full with 10% legit files and 90% bullshit (unpurged deleted files), it has to copy all of the legit user data to cache, erase the cells to clear the 90% useless data, modify the cache's data with what YOU want to write, then copy it all back. This is called write amplification, because the amount of data being moved around is an amplified amount, relative to the data you're actually looking to write.
The ATA TRIM command deletes the file from the NAND cells the minute they're deleted in the OS, so the cells only ever contain active user data. The only time it would have to perform this read/erase/modify/write action is if the cells it wants to write to are 100% full with real user data.
Obviously this extra file juggling does have some longevity considerations, but they're minimal. The real benefit of TRIM is an SSD that does not sharply degrade in performance over time through simple usage.
As for your longevity questions, i.e. "How long do I have before this drive is dead?" That is exactly what I am looking to answer and, possibly, clear the air about. I don't have a clear answer for that yet, because every drive controller has a different write amplification factor that can be as big as 40:1, or as little as 1.1:1. If my research pans out, I will be able to say "These SSDs are good for XXXGB of data per day for XXX years." That is my goal.
Very interested in an article and recommendations. I have the OCZ Vertex and as I am about to put Win 7 on three computers over Turkey Day. I'd like to make sure I install the OS correctly on the SSD with TRIM firmware and Win 7.
Do not full format the disk. Quick format only.
Can't wait to read your article !
Still eagerly awaiting the article, but thanks for the executive summary. I already had setup the SSD as my boot drive and apps only as well as disabling the Window Search. However, I had forgotten to move the swap file, to disable Superfetch, and 8.3 filenames. Many thanks.
I have a swap file on my 7 installs, I have not gone to tweaking that yet.
Is it in Performance options / advanced tab / virtual memory ?
I can disable the swapping on C: and enable it on my D: , is it how we can do it ?
Just curious since i will buy and SSD drive sooner than later
As a hard and fast rule, any writes to an SSD not made by the user are a bad idea.
Looking forward to seeing how costly SSD writes are in practice.
If you are not using an OS that supports TRIM, you want an SSD running a FW that has "Garbage Collection" (OCZ's term for it) or whatever the manufacturer puts in place to keep free blocks available.
Version 3.0 of the SSD list is here! This is the second largest update this document has received since it was expanded to include the current information sets.
As you can see below, several new SSD series have made the list, including a first-time showing by Mushkin, which has finally published TRIM data.
Finally, I'm still on the lookout for the information requested in the "wanted" section. If anyone has any particular insight on these topics, a PM would be greatly appreciated.
Cheers!
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