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iMac 27" SSD Upgrade - Important Tip!
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I might have gone for that if it wasn't so expensive.
Intel G2s hardly degrade which is a major region I chose them. Everyone goes on about TRIM, but it's useless in OS X and it's useless on a G2.
The superdrive is not a 5.25" drive, it's a slim optical drive. You won't fit any 5.25" drive or caddy in there.
Thanks for your quick response, so reading up more on ssds and the imac, i take it that the only way to install a ssd in the drive bay is to get the drive bay enclosure from the ifixit site for $60? Has anybody on here successfully completed this?
I think that with a little bit of double-sided tape, one could install it without the enclosure.
Go to the download page for the new firmware, there's a readme.txt and release notes available to read, but in summary you download the .iso file, burn it using Disk Utility then shut down the computer fully with the CD already in. It says to wait around 15 seconds before powering up (holding down 'c' to boot from the CD) then follow the instructions. Once you're done, power down and wait 10 seconds then start up as normal.
Yes, of course I am using software RAID0. There are only two SATA ports inside the iMac (none outside), so you need to remove both the ODD and HDD if you want two SSDs. I don't know of any device with RAID0 built into a 3.5" HDD size box that allows for two 2.5" SATA drives, but doing this would still limit you to the 3Gb/s of SATA.
I attach the results of my benchmarks. I did each test twice (a and b).
I'm not convinced Xbench is very useful, and without examining the results closely, I chose 128K.
Running the system, to write a 1GB file using dd went at 154MB/s and reading it using dd went at 285MB/s. However reading it again with dd and bs=1000m went at 1.4GB/s and cating it > /dev/null was much the same speed, so I guess there was some kind of cacheing going on.
If nothing else, this proves using two drives, my write speed has doubled, as 80GB G2s only get around 80MB/s on their own.
Where do you live?
I would pay you to do mine if you are close enough to me.
Could you please elaborate on that? I've read a certain amount on SSDs, but I guess I don't have a very firm grasp on all the issues.
When I originally came across TRIM, I got worried that it's seemingly not available on OS X. I mean, Intel developed it for a reason, not just for the heck of it. Are you implying that OS X does not degrade SSDs while Windows does? That doesn't seem very plausible, but what do I know - can you give a link showing that? Assuming degradation happens, I find it puzzling that you'd say "Intel G2s hardly degrade which is a major reason I chose them." I mean, if it was useless, why would Intel develop TRIM? That doesn't make sense at all - and Intel put in a lot - a lot of effort into TRIM and correcting the initial bugs. They would hardly bother if it made little difference or no difference.
I want to understand why TRIM is "useless on OS X". If OS X doesn't support TRIM, I see that as a negative that hopefully Apple corrects and catches up with Windows. SSDs are the future. It doesn't make sense for Apple to fall behind on the major storage revolution that's coming down the pike - not if it wants to claim the crown of having "the most advanced operating system".
I do want to install an SSD - clearly it seems there are major advantages to it. But I'm gonna wait until a few things happen - all of them hopefully soon. First, the price per GB has to come down to a more reasonable level - I'm not talking equal to present day spinning discs, but, say, so that I can buy 500GB for $300. Second, some further standardization has to happen for SSDs. Third, there still remain a few technical problems and I want to see some longevity studies that show that I can trust these drives not to crap out too soon or too suddenly. Fourth - and it pains me to say this - I hope Apple and OS X gets onboard the train, and leads the way, instead of being a distant laggard behind windows in supporting this vital technology.
What is the status of TRIM and other software support for SSDs on the mac platform? Thanks for taking the time to answer these questions/concerns!
He says "hardly degrade", but I think he should be saying they don't degrade as much as every other SSD on the market.
The Intels still degrade, pretty significantly so:
Code:
4KB Random Write, IOQ=16___________Run 1_________Run 2
Intel X25-M 80GB TRIM Firmware_____37.9 MB/s_____13.8 MB/sBut PLEASE note that the 14 MB/s Random Writes are higher than most SSDs and all HDDs if I'm not mistaken.
But to say they don't degrade (without TRIM) is a joke. Intel has just employed much better write combining algorithms, as well as other things to ensure the drive is still usable even if it's entirely full.
Your concerns about SSD longevity are common, but there is no real reason. If you write like 5GB a day to an Intel SSD the wear leveling algorithms ensure that the drive will last 1000 years before it's an issue. The actual longevity issue regards the length of time that NAND cells can hold their charge, and I think they last for only about 10 years. I find this point moot, since I have never kept the same drive for 10 years. Ever. And I don't think anybody does. If they want long term STORAGE, and not USAGE, there are much better methods of storing the data.
you download the new firmware .iso from intel's site, burn it with diskutlity and restart your mac holding "c" ..
the rest explains itself
No, I'm not saying OS X doesn't degrade SSDs, I'm saying that G2s dont degrade on either platform.
From the same website jonwd7 posted against my argument:
Intel bothered with TRIM because originally it was good idea. Since then, the garbage collection has improved significantly and it is less necessary. I'm not saying it's useless, but I think the main reason Intel are hurrying to get their firmware updated to support it is that it ticks another box for the marketing department. I really wouldn't get hung up over it. With or without TRIM, you will be getting a SIGNIFICANT improvement, and by the time you want to upgrade again, there will be more significant improvements (that don't rely on TRIM, but perhaps will need SATA 6Gbps).
OS X doesn't support TRIM, and so, it is useless for 'us'. Maybe Apple will catch up, but I don't expect it any time soon. If/when they do support it, it will probably have lost even more value. (Rather like Blu-ray).
Of course it's always nice for prices to drop, but prices are always going to drop more and more, so if you keep waiting, you'll never buy. (At least you have a target price, OldCorpse). I'm not sure what you mean by 'further standardisation' but in regards to longevity, I use TimeMachine, and don't care if the thing craps out.
mariuscmorar: HA5
knewsom: You can't use double-sided-tape. The iMac is curved where you'd be trying to stick it. Have a look at my pics to see what I did, but I it isn't very secure, and I wouldn't recommend it for anyone who moves their iMac regularly (or at all
).
From the same website jonwd7 posted against my argument:
Src: http://anandtech.com/storage/showdoc.aspx?i=3631&p=11
Intel bothered with TRIM because originally it was good idea. Since then, the garbage collection has improved significantly and it is less necessary. I'm not saying it's useless, but I think the main reason Intel are hurrying to get their firmware updated to support it is that it ticks another box for the marketing department. I really wouldn't get hung up over it. With or without TRIM, you will be getting a SIGNIFICANT improvement, and by the time you want to upgrade again, there will be more significant improvements (that don't rely on TRIM, but perhaps will need SATA 6Gbps).
OS X doesn't support TRIM, and so, it is useless for 'us'. Maybe Apple will catch up, but I don't expect it any time soon. If/when they do support it, it will probably have lost even more value. (Rather like Blu-ray).
Of course it's always nice for prices to drop, but prices are always going to drop more and more, so if you keep waiting, you'll never buy. (At least you have a target price, OldCorpse). I'm not sure what you mean by 'further standardisation' but in regards to longevity, I use TimeMachine, and don't care if the thing craps out.
mariuscmorar: HA5
knewsom: You can't use double-sided-tape. The iMac is curved where you'd be trying to stick it. Have a look at my pics to see what I did, but I it isn't very secure, and I wouldn't recommend it for anyone who moves their iMac regularly (or at all
).I'm sorry but you are wrong. On a full drive the Random 4K writes plummet from ~40MB/s ('new') to 14MB/s...
To quote them on the page in which I already linked:
The other tests go on to show that performance does NOT degrade if you can manage to format the entire drive, or delete all files. These are the only ways to achieve zero degradation without TRIM support.
I'll include the link again so you don't have to fish for it in my post above: http://www.anandtech.com/storage/showdoc.aspx?i=3667&p=2
Just because they mention how the PCMARK SCORES do not degrade does not mean the actual numbers do not degrade. The simple conclusion is that the PCMark test suite is not very rigorous, and cannot catch the degradation happening, and therefore is FLAWED.
So if you use the drive on OS X, without native TRIM support, you will have degraded performance on a full or partially full drive.
And does it matter? Yes and no. You're paying for Intel-level performance, but the Random Writes when fully degraded are at the level of other SSDs. Do Random Writes matter? Yes and no. Either way they still end up faster than 95% of all other drives, even fully degraded. Random reads are the most important and clearly a full drive or lack of TRIM support are not going to affect those. So I would still always suggest getting an SSD, regardless of degradation.
Perhaps you are correct that G2 does degrade, but I don't accept that it gets as bad as others. This whole conversation is moot, since there is no TRIM in OS X. If you want an SSD, you need the one that performs best without it, i.e. Intel G2.
Edit: Look here for used state performance of different drives: http://anandtech.com/storage/showdoc.aspx?i=3631&p=22
If there is something wrong with the chart, please enlighten me.
Edit 2: Later in the article you link to:
Edit: Look here for used state performance of different drives: http://anandtech.com/storage/showdoc.aspx?i=3631&p=22
If there is something wrong with the chart, please enlighten me.
Edit 2: Later in the article you link to:
I know this is out of context.
Conceivably, if your entire system is well backed-up on a redundant drive, couldn't you just entirely reformat the SSD when it begins to degrade? Say, every two years or so until it no longer answers, at which point one must replace it?
What kind of factory warranties usually accompany SSD's?
What kind of factory warranties usually accompany SSD's?
I'm not sure if that would work either. You could certainly use Windows with TRIM support to do it, or run the maintenance tools.
Well, that's pretty simple, I intended to do a dual-boot with Win7 anyhow. (well, really a tri-boot, adding Ubuntu to the mix)
In that case, one doesn't need to necessarily shell out for the Intel brand name. How much space does one actually NEED for a system drive with /Users on a separate HDD?
Depends if you want apps like iLife, Office and CS4. A basic system can fit on <20GB, but you shouldn't run it almost full, and extra space are needed for things like sleep-image (same size as the amount of RAM you have) and caches.
leave some space free
Another method to prevent speed degradation is to leave some of the drive empty when you partition it.
I have seen various recommendations and I'm sure that someone here will have a better estimate, but I think what I read said that 15% free space was enough, so just partition the drive to less than it's capacity and then performance should be preserved (of course this means that you have less space, but seems like a fair trade off to me).
Also, curious if anyone has tried using the miniPCIe connector for an SSD drive yet (or for that matter an eSATA connector)....
ps. thanks for the benchmarks.
pps. has everyone seen the threads on the Mac Pro forum talking about disk corruption with software RAID0 on SSDs with the latest update of Snow Leopard... looks like there is an unspecified problem and they're suggesting not upgradin at the moment...
Another method to prevent speed degradation is to leave some of the drive empty when you partition it.
I have seen various recommendations and I'm sure that someone here will have a better estimate, but I think what I read said that 15% free space was enough, so just partition the drive to less than it's capacity and then performance should be preserved (of course this means that you have less space, but seems like a fair trade off to me).
Also, curious if anyone has tried using the miniPCIe connector for an SSD drive yet (or for that matter an eSATA connector)....
ps. thanks for the benchmarks.
pps. has everyone seen the threads on the Mac Pro forum talking about disk corruption with software RAID0 on SSDs with the latest update of Snow Leopard... looks like there is an unspecified problem and they're suggesting not upgradin at the moment...
symlinks
If you're worried about fitting all your apps on the SSD, size may become an issue (especially with bloatware apps).
However, some judicious use of ln -s /OtherDrive/MyAPP /Applications/
can work wonders, you can even go more fine grained and move individual directories, for instance clip art to a slower drive.
I guess the same could be done for suspend images, which may become quite huge with a lot of RAM, but should be sequential read/writes to disk.
If you're worried about fitting all your apps on the SSD, size may become an issue (especially with bloatware apps).
However, some judicious use of ln -s /OtherDrive/MyAPP /Applications/
can work wonders, you can even go more fine grained and move individual directories, for instance clip art to a slower drive.
I guess the same could be done for suspend images, which may become quite huge with a lot of RAM, but should be sequential read/writes to disk.
No no no, what you're talking about has nothing to do with the performance degradation issue of SSDs. On all SSDs (because they use NAND flash) you have pages and blocks. Usually pages are 4K of data each, and blocks are 128 pages. You can read from and write to pages, but you must erase entire blocks at a time. You cannot erase individual pages. If a block is full of invalid pages (files that have been overwritten at the file system level for example), it must be erased before it can be written to.
Don't forget that with ALL HDs, SSD or otherwise, when you "delete" something in the OS, the file is not actually erased, the OS just tells the HD that the space where the file was can be overwritten. This is a problem with SSDs because you can write to a much smaller segment of the drive then you can erase. If you have a block that has 8 deleted pages and 120 active ones, and you need to write to those 8 deleted pages, what the drive actually has to do is copy the 120 valid pages into spare memory, erase the ENTIRE block, then copy back those 120 pages it saved plus 8 new pages you are writing.
So even though an SSD is MUCH faster, after being heavily used you will sometimes run into situations where to write 8 pages, you actually have to read 120 pages, erase 128 pages, then write 128 pages, all just to write 8 pages. However, SSDs are SO fast that this is still MUCH faster than an HD writing 8 pages. Just not as fast as the day you bought the SSD new.
However, the G2 Intel SSDs have a new controller and firmware that seem to do some sort of magic that makes them somewhat immune to the performance degradation issue. Some speculate that since they have much more cache they are able to copy and overwrite blocks much faster.
4K random reads and writes are the most important speed benchmark for SSDs if you are planning on using them as you boot drive. These are the operations that the OS does a lot and having them sped up will make your computer "feel" the fastest. So not only is it faster on paper, but it's actually in such an important area that the difference seems amplified to the user.
Here are some benchmarks comparing the Intel G1, G2 and HDDs
4KB Random Write (New) - MB/s
-X25M G2: **36.1**
-X25M G1: 40.8
-WD 10,000 RPM Raptor: 1.5
-Seagate 5400 RPM Drive: 0.8
4KB Random Write (Used) - MB/s
-X25M G2: **35.8**
-X25M G1: 26.3
-WD 10,000 RPM Raptor: 1.5
-Seagate 5400 RPM Drive: 0.8
So you can see, where the Intel G1 drops from about 40MB/s to 26MB/s after being heavily used, the G2 goes from 36.1 to 35.8. Hardly any change. That being said, even the "degraded" peformance of the G1 at 26.3MB/s RAPES the 10,000 RPM raptor HDD at 1.5MB/s or the embarassing 0.8MB/s of a laptop HD.
So basically with the G2 TRIM is less important. However that number you posted without TRIM is also from a test on Anandtech, so basically his earlier tests said it didn't matter, now that TRIM is out he says it does, so it's a little mysterious...
Anand did an earlier article on the same Intel X25 M G2 where he said without trim the drop from new to used was 36.1 MB/s to 35.8MB/s. Now that TRIM is out he's saying it drops from 40 to 14... so the tests are not very consistent
http://www.anandtech.com/storage/showdoc.aspx?i=3631&p=22
If you just do a reformat with something like Disk Utility it will actually make the problem worse. You would need to use the Intel software tools for the drive. They only work in windows but that's obviously not an issue if you are using bootcamp like many of us likely will be.
Well I'm already spending $549 for the drive, $75 for the installation, $60 for a new external optical, all plus tax (Canadian dollars) so about $766. So I'm definitely willing to spend another $60 to have a proper enclosure vs tape.
"No, no, no"?? Did you even read what you quoted from me?? I was specifically addressing someone's question about LONGEVITY... Not about performance degradation. Before you tell me I'm "all wrong" about something make sure you have some idea of what I'm speaking about. I was trying to explain to this person that an SSD will last as long as they will probably need to use it before they get another SSD, so the LONGEVITY concerns are not a concern at all.
In fact I'm aware of every single thing you posted, probably more so, but thanks for the lecture about how SSDs work.
As for the inconsistent benchmarks in regard to Random Writes, who knows... That kind of concerns me, but at least the "degraded" numbers are higher than most other drives in existence.