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How do MBAs SSD sustain itself with no TRIM?
- Thread starter kkel19
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It's probably a moot point since TRIM is on its way. The latest MacBook Pros ship with a special version of OS X 10.6.6 that enables TRIM. That means it is likely we'll get an update that supports TRIM, as well. If not, it's almost certain that Lion (10.7) will have TRIM support.
Until then, the Toshiba and Samsung drives that Apple uses in its current models do support garbage collection, which helps maintain performance.
Until then, the Toshiba and Samsung drives that Apple uses in its current models do support garbage collection, which helps maintain performance.
I thought that TRIM has to be supported by both hardware and support, and not just by one or the other?
both hardware and software must support trim
So does that mean our SSD in the MBA support TRIM? If I understand correctly, OSX Lion supports TRIM from the "software" level but if the default SSD's in the MBA on the "hardware" level, then there is no TRIM functionality?
I guess what I'm really asking is that when OSX Lion comes to the table in summer, will our new MBA's have TRIM support via hardward and software?
So does that mean our SSD in the MBA support TRIM? If I understand correctly, OSX Lion supports TRIM from the "software" level but if the default SSD's in the MBA on the "hardware" level, then there is no TRIM functionality?
I guess what I'm really asking is that when OSX Lion comes to the table in summer, will our new MBA's have TRIM support via hardward and software?
yes the mba (late 2010) hard drives support trim
So does that mean our SSD in the MBA support TRIM? If I understand correctly, OSX Lion supports TRIM from the "software" level but if the default SSD's in the MBA on the "hardware" level, then there is no TRIM functionality?
I guess what I'm really asking is that when OSX Lion comes to the table in summer, will our new MBA's have TRIM support via hardward and software?
Yes, the drives in the current MacBook Air support TRIM. You can tell that since TRIM is active in a Windows 7 Boot Camp partition on them.
Phew...that is good to know! I was starting to get concerned that my 3 day old 13" MBA Ultimate did not have a SSD with TRIM support for when OSX Lion arrives.
Windows thinking! Trim is for Windows machines with SSD's. And just like you need to degrag their sorry hard drives you need to trim their SSD's. Macs are different. The Mac OS doesn't mess up the drives like Windows, that craps all over everything.
Actually, any amount of writing and deleting will cause an SSD's performance to degrade. The Toshiba and Samsung drives that Apple uses do a lot of OS-independent "garbage collection" that helps, but TRIM support will still come in handy.
Do a search on the internets for the MacWorld torture tests that proved that ain't so.
As you probably know, data is never really "deleted" from a file system -- the file's name is removed and the data is added to a list of "free space."
On a first gen SSD, these "free space" blocks become interleaved with "actually used in files" blocks. Unfortunately, in order to reclaim space on part of an SSD block, you have to clear and re-write the entire block. Magnetic hard drives, for which all existing drivers and file systems were designed, do not have this limitation. The end result was write pauses as drives aged, and more of their free space was interleaved with real data.
Second gen SSDs got around this by using idle time garbage collection, wherein drives that are not busy go through written blocks looking for deleted data. Each block must be checked individually, there's no "hit list," and so idle GC is an inefficient way to clear up blocks. For laptop users who frequently close their lids, there isn't as much GC as there is for a server user and thus idle GC is less useful.
TRIM takes this to the next level, proactively identifying blocks with free space on delete and making garbage collection much more efficient.
TRIM will play nicely on any "stress test" that has a server-like load -- where data is in constant motion without extended (minutes or longer) periods of rest where GC can run a full cycle. In "real world" desktop/laptop tests, TRIM is not magic or even a necessity; many users will not notice much difference beyond idle GC. Users without idle GC (such as my first gen SSD at work) will notice a HUGE difference between garbage collection and none, regardless of the collection technique (idle or TRIM). Drives using alternative storage techniques, such as the SandForce controller, should not notice any difference with TRIM since storage is allocated much differently.
On a first gen SSD, these "free space" blocks become interleaved with "actually used in files" blocks. Unfortunately, in order to reclaim space on part of an SSD block, you have to clear and re-write the entire block. Magnetic hard drives, for which all existing drivers and file systems were designed, do not have this limitation. The end result was write pauses as drives aged, and more of their free space was interleaved with real data.
Second gen SSDs got around this by using idle time garbage collection, wherein drives that are not busy go through written blocks looking for deleted data. Each block must be checked individually, there's no "hit list," and so idle GC is an inefficient way to clear up blocks. For laptop users who frequently close their lids, there isn't as much GC as there is for a server user and thus idle GC is less useful.
TRIM takes this to the next level, proactively identifying blocks with free space on delete and making garbage collection much more efficient.
TRIM will play nicely on any "stress test" that has a server-like load -- where data is in constant motion without extended (minutes or longer) periods of rest where GC can run a full cycle. In "real world" desktop/laptop tests, TRIM is not magic or even a necessity; many users will not notice much difference beyond idle GC. Users without idle GC (such as my first gen SSD at work) will notice a HUGE difference between garbage collection and none, regardless of the collection technique (idle or TRIM). Drives using alternative storage techniques, such as the SandForce controller, should not notice any difference with TRIM since storage is allocated much differently.
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stockscalper is right that when Macworld tested the new SSD's in the Air performance did not substantially degrade after torture tests and re-installing the OS.
This was an interesting result and there are a several explanations for why this might be true.
However, one explanation that is definitely wrong is that somehow OS X doesn't "mess up" SSD's like Windows does.
Performance degradation of SSD's on Mac's have already been proven a variety of SSD's in the past. Newer SSD's are much better at garbage collection which partially explains the Macworld results.
If it were true that OS X doesn't "mess up" SSDs like Windows does, then we would expect to see that all SSDs (not just the newer ones found in the Air), including those without garbage collection, do not experience performance loss over time. But this is not the case.
In any case, a lot of results have shown that newer SSDs with garbage collection (beginning with the SF controllers) do a much better job of retaining performance over time than the first wave of SSDs. TRIM might still be helpful in the long run but it's not a big of a problem as it was so I wouldn't worry too much about it, especially since TRIM is coming soon to OS X anyways.
This was an interesting result and there are a several explanations for why this might be true.
However, one explanation that is definitely wrong is that somehow OS X doesn't "mess up" SSD's like Windows does.
Performance degradation of SSD's on Mac's have already been proven a variety of SSD's in the past. Newer SSD's are much better at garbage collection which partially explains the Macworld results.
If it were true that OS X doesn't "mess up" SSDs like Windows does, then we would expect to see that all SSDs (not just the newer ones found in the Air), including those without garbage collection, do not experience performance loss over time. But this is not the case.
In any case, a lot of results have shown that newer SSDs with garbage collection (beginning with the SF controllers) do a much better job of retaining performance over time than the first wave of SSDs. TRIM might still be helpful in the long run but it's not a big of a problem as it was so I wouldn't worry too much about it, especially since TRIM is coming soon to OS X anyways.
Wait for OS10.6.7, which is coming soon...
10.6.7 is available now
And no there's no trim
Actually, TRIM works in the short term. TRIM helps when you delete a file by telling the SSD drive that some space doesn't contain valid data anymore. That means the drive doesn't need to use garbage collection for that area, because it _knows_ the area is unused.
Let's say you delete 10 MB of data, and then you add 10 MB again, and the OS reuses the 10 MB that were just deleted. With TRIM, the drive _knows_ that the 10 MB are unused and filling with 10 MB of new data is quick. Without TRIM, re-using these 10 MB is slower. However, once the 10 MB have been rewritten, TRIM or no TRIM makes no difference anymore.
