An SSD falls from the Apple tree.

August 8, 2010 3:06 AM

The new iMacs: What are the risks of purchasing an iMac with a solid state drive?

Two weeks ago, Apple released its updated line of 27" iMacs, and for the first time ever, the company includes the option of buying a preinstalled solid state drive. Apple allows buyers to configure their machine with a either a single SSD, or an SSD running in tandem with a conventional hard drive.

Comments for this this post mention a few of the drawbacks of the SSD configuration scenario, such as the fact that OS X doesn't support TRIM, and therefore isn't entirely optimized for SSDs. Also, I've heard that current SSDs are sometimes prone to degradation.

Since Apple's SSD option is pricey, my budget only allows for a SSD (and no HD) along with the Intel i3. Yes, I realize that the $600 price tag will drop precipitously in a few years, but it's the only option from Apple at the moment, and I'd prefer to buy a lesser processor and SSD rather than install a third-party drive myself. I'll only store about 100 GBs of data, so the OS will have plenty of room for virtual memory.

In my case, the SSD will hold OS X, applications and all user data (including local backups of Dropbox files).

-What are the risks, in terms of data loss, corruption, degradation and the like, of SSDs? Are they prone to crashes or data loss, like the early HDs of many years ago? Is the risk of data loss markedly higher than the HD Apple would install?
-Does degradation exist? If so, how will it effect the usability of the drive, in terms of read/write speeds, data corruption and the like? Will the drive be noticeably slower two years from now?
-Is their any way to judge if Apple uses a reliable model for its SSD?
-I know that SSDs are whisper quiet and fast, but are they dramatically faster than HDs for loading programs such as the OS at boot, Microsoft Word/Excel, iPhoto/iTunes and the like?

I'm a total newbie when it comes to SSDs, but it seems like an interesting technology. Please comment away.

posted by Gordion Knott to computers & internet (10 answers total)

I've heard that Apple uses Samsung SSD drives which aren't as good as aftermarket SSDs you could install yourself (with varying degrees of difficulty).

I think in part you've answered your own question. Mac OS X doesn't yet support TRIM, so the disk could quickly become erroneously "full" and in fact, begin to perform worse than a traditional hard disk. I don't think I'd run a Mac solely from a SSD drive yet. I happily run a Windows 7 box from one, though. Windows 7 supports TRIM.
posted by dance at 4:31 AM on August 8, 2010

My opinion is that, like any new technology, one should wait until the 3rd generation or so before buying. SSDs are very new to the computing market, and we are certain to see massive improvements in the technology in the next two years.
posted by Vindaloo at 4:36 AM on August 8, 2010

The NAND memory cells used in SSDs can be erased and rewritten a limited number of times, which does put a definite lifetime on the drive. However that number is typically in the millions and the drive itself has ways to mitigate the problem by invisibly remapping sectors to distribute the wear evenly (wear leveling). This has always been a concern about SSDs but I think most people now agree that their lifetime is on average at least as long as hard drives and probably longer -- but of course it depends on how they're used because only writes cause wear.

Degradation is a definite reality due to write amplification, but it just means that the write speed gradually decreases with usage -- read speed is unaffected. And it can be completely reversed by doing a drive reset/format.

As to performance, SSDs only outperform hard drives by a relatively modest amount when it comes to sequential IO -- we're talking write speeds roughly in the neighborhood of maybe 50-100 MB/s and read speeds of 150-200 MB/s, which is not a whole lot faster than a HD, and even slower in some corner cases. But what they do excel at is having virtually no seek time which means they far outperform hard drives when it comes to booting the OS and starting programs, and other tasks that involve random IO as opposed to sequential (streaming/bulk) IO.
posted by Rhomboid at 4:45 AM on August 8, 2010 [1 favorite]

one should wait until the 3rd generation or so before buying

That point has been reached a long time ago. For example from this page on Samsung's site (since Apple is using Samsung drives):

Samsung released its first 32GB SSD (PATA) in March 2006, followed by a 64GB SSD in June 2007 and its 128GB SATA II SSD in July 2008. Mass production of the 256GB MLC-based SSD began in November, 2008

Based on that this is a fourth generation part.
posted by Rhomboid at 5:06 AM on August 8, 2010

My opinion is that, like any new technology, one should wait until the 3rd generation or so before buying.

I'm a longtime Apple user FWIW but this statement is especially true with Apple.
posted by jeremias at 7:47 AM on August 8, 2010 [1 favorite]

Based on that this is a fourth generation part.

Having released four models doesn't mean it's a fourth generation part. A capacity change could still be using the same fundamental technology.

OP, is it possible to hold off buying the iMac until you save more? Going for a SSD/i3 combo seems a bit limiting. Maybe it's only a psychological thing but I don't know if I could pick the high performance drive and then go for the (comparatively) low-end processor, even if I wasn't doing much that was limited by processor speed.
posted by 6550 at 9:56 AM on August 8, 2010

I decided to put a 256GB SSD in my Macbook Pro last year after having done some research. The most important thing for me is to limit the number of extraneous writes - this meant turning off noatime, and some other things.

Drive access is FAST, and write speeds are in the 115-130 MB/sec (reads are up to 220 MB/sec, which is what I needed for some database access).
posted by aberrant at 10:07 AM on August 8, 2010

I have a MacBook Pro 13" with the SSD (the 128GB model). bootup time and application launches are quite noticeably faster than my Core i7 27" iMac (first-gen, with 1TB SATA disk), even after factoring in the differences in what starts up on each from a fresh boot. the MacBook is the 2.53GHz Core 2 Duo and has half the RAM (4GB vs. 8) than the iMac. actually using the computer is different, though; the iMac is obviously faster when I'm actually doing stuff on it. the only thing I really regret about it is not getting the larger 256GB one - I usually keep a few VMs and Windows 7 in Boot Camp on it and space gets kinda tight on the 128GB model. I haven't noticed any speed degradation on it, though keep in mind that it's not my primary computer, and I haven't had the machine for very long (just under 1yr). I have no idea what brand of drive it is - Apple puts custom firmware on there and it IDs itself as an "APPLE SSD", though it seems it's a Samsung drive.

I wouldn't worry too much about not having TRIM - while it's not there right now there's no reason it can't be rolled into a future OS release. SSDs are already mostly out of their awkward toddler phase, I think; there's been a lot of optimization of controllers and memory chips and all that over the past few years. I think it's also a good idea to keep in mind that both SSDs and spinning disk hard drives are going to fail at some point, and that you ought to have a backup regardless of what you buy, though the SSD ought to be more reliable than the regular hard drive. anecdotally, I haven't heard of SSDs getting swapped out much, but that may have more to do with the number of people buying them than anything. (I hear more about MacBook drives getting swapped than anything. also anecdotally, my last two iMacs have chewed through a spinning-disk hard drive in roughly 1.5 years each.)

personally, for a desktop machine, I'd stick with the 1TB disk and spend the money on a backup drive and more RAM. SSDs are nice and all but they're pretty expensive for what you get (especially through Apple, though there are options available) and they really don't do much for you past starting applications/booting the computer. having fast VM is good but 8 or 16GB of RAM will likely keep you from using it much anyway. it depends on what you're doing or what you want out of it, though.
posted by mrg at 10:39 AM on August 8, 2010

Having released four models doesn't mean it's a fourth generation part.

And having been on the market for 4.5 years also doesn't mean it's a 'new technology'.
posted by Rhomboid at 10:47 AM on August 8, 2010

TRIM support appears to be less important (far less important) in OS X than Windows:

http://www.bit-tech.net/hardware/apple/2010/07/01/mac-ssd-performance-trim-in-osx/7

I have an SSD (self-installed Intel) in my MBP and I wouldn't go back. But, I only paid 229 for an 80 gig drive. I would not pay 600 for an SSD that isn't best of breed. My computer is dramatically faster (I5) with the SSD than without.

As with any hard drive, backups are critical. My guess is that SSDs are more reliable than platter drives- unless you upgrade the firmware and have your drive bricked. I still back up regularly.
posted by jz at 11:13 AM on August 8, 2010