SSD formatted capacity 55.5GB??

[Beliyaal]

If apple have implemented performance enhancements for random writes by using the space i will forgive them.

For information about how it could work check out this:
http://managedflash.com/technology/solution.htm

We should be able to tell with if they have done this by random write benchmarks.

 

[Mactagonist]

I am glad you are still persuing this. It is very odd.

 

[dbell]

If you look at the opened SSD drive there are 12 chips.

I've never seen or heard of a 5.333 GB chip.

It's more likely they are 5.0 GB each and the drive is actually 60GB.

 

[izibo]

Flash memory isn't perfect. Some of the bits will get "stuck" after time. I am guessing that the extra 4gb is sequestered as some sort of fall-back when a bad bit is discovered. That way, you never know the difference...

 

[Beliyaal]

If you buy a 64 GB drive it should make 64 GB available. All other flash drives in the market already have reserved space and still delivers the number of bytes promised.

As stated the Anandtech review the drive makes available 64 billion bytes as it should be. I'm guessing this will lead to class action if Apple doesn't have a really good explanation.

 

[Schmoe0013]

Flash memory isn't perfect. Some of the bits will get "stuck" after time. I am guessing that the extra 4gb is sequestered as some sort of fall-back when a bad bit is discovered. That way, you never know the difference...

I'm sorry, but this is full of inaccuracies... I am too tired right now to comment, but if you are talking about using 4 gigs of bits as a parody bit? also, "stuck" bits over time? please explain what you mean, because at first glance, i didn't know how to interpret that, because really, it means nothing...

 

[econ-mit]

also annoyed

I am also annoyed at this and just wanted to add my voice of discontent to this thread. My Air has a 55.58G capacity. With the OS and apps pre-installed my free space started at 37G. Needless to say, every giga counts when you are this low and I feel we need an explanation for these ~4G that seem missing.

Right now, it does seem that the most plausible explanation is that this is not really a 64G drive but something closer to a 60G. (If that photo posted above provides the clue.) That is not what we paid for.

Let us also remember that Steve Jobs when he introduced the Air declared that the SSD was pricey but "super fast". I trusted him enough to put up the $$$ for it. Given the benchmarks, I think that statement was also a bit of a stretch, and perhaps even fair to say that it was misleading. Some might even say false advertising? I don't know, I could still be happy with my SSD for its higher durability, but now that I feel slightly cheated out of a few Gigs..

I hope we get to the bottom of this. Please let me know if anyone finds anything out.

 

[krye]

If you look at the opened SSD drive there are 12 chips.

I've never seen or heard of a 5.333 GB chip.

It's more likely they are 5.0 GB each and the drive is actually 60GB.

If you knew Binary then you'd know that a 5G chip doesn't exist.

 

[whozurdaddy]

I apologize for the delay in this post. I had a reply typed up which I thought I submitted but I guess it got lost at some point.

I posted a new thread on the Apple forum here (the "pre-release" MBA forum is now closed) but it hasn't gone anywhere.

I called Apple support on 2/15. I spoke to someone named Brad. Since he wasn't that knowledgeable when it came to SSD so he got in touch with a product specialist. Brad was very friendly, but unfortunately he didn't have an answer. He said he found an internal KB article that stated 55.6GB was the 'correct' capacity of the drive but there was no explanation why. I gave him the URL to Anand's review along with my Apple forum post. He said he would open a ticket and include the URL's I gave him. So far I haven't heard anything.

 

[profiteor]

I'm sorry, but this is full of inaccuracies... I am too tired right now to comment, but if you are talking about using 4 gigs of bits as a parody bit? also, "stuck" bits over time? please explain what you mean, because at first glance, i didn't know how to interpret that, because really, it means nothing...

Not to speak for someone else, but...

I think izibo meant that these are portions of the drive reserved to implement sector remapping/byte remapping when bits fail. This is standard practice in rotational hard drives, except that this is typically done with media NOT part of the advertised size (for example, advertised 160GB drives made with 200GB platters have 40GB of remap available; this is an example, rarely do vendors waste that much space).

I don't think flash drives have built-in remap, since they are advertised at a power of 2, and chips come as a power of 2, and that would be extra cost to add more chips. Slightly shaky logic, but I'm going with it.

 

[mtk75]

If you look at the opened SSD drive there are 12 chips.

I've never seen or heard of a 5.333 GB chip.

It's more likely they are 5.0 GB each and the drive is actually 60GB.

It's actually much more likely that there are 4 more flash chips, a controller chip, and a lot of passive components on the side of the circuit board that we can't see in the photo.

My guess is that each chip is 4 GB of usable space. The parity for dealing with dead bits is actually built into each flash page. The pages are 512 bytes with 16 byte parity sections built on to the back. The erase blocks are 32 pages. Sometimes the erase blocks go bad, so there need to be a certain number of them held back for replacement of bad blocks.

I'm certain that there are also many blocks held back to make the wear leveling algorithms easier. Depending on how the algorithm works, I would bet on erase blocks being used for multiple files, so there may be a need for the drive to move things around sometimes in order to delete other information.

BTW, you don't need to take my word for all this, but I do program embedded firmware which uses these parts directly, very similar stuff to the controller chip in this design...

-Matt

 

[Consultant]

Let us also remember that Steve Jobs when he introduced the Air declared that the SSD was pricey but "super fast". I trusted him enough to put up the $$$ for it. Given the benchmarks, I think that statement was also a bit of a stretch, and perhaps even fair to say that it was misleading. Some might even say false advertising? I don't know, I could still be happy with my SSD for its higher durability, but now that I feel slightly cheated out of a few Gigs..

Yes, SSD has fast random access. Benchmarks:
http://www.barefeats.com/macair1.html

 

[cowm007]

...but if you are talking about using 4 gigs of bits as a parody bit?...

I think you meant parity bit. A parody bit is something a comedian would do .

 

[econ-mit]

Yes, SSD has fast random access. Benchmarks:
http://www.barefeats.com/macair1.html

Yes, but write is so much lower than in typical real world use the gains have been reported as small and even negative for some tasks.

To be clear, I'm not saying I am totally unhappy with an SSD, there are pros and cons. But I think that, given the high cost, the advertisement of the true benefits could have been a bit more informative and precise.

Maybe I am being Utopian about what a company might disclose about its own products. But everyone here is a fan of Apple in some ways and believes Apple should be better than other computer makers on many dimensions, and that could include transparency about its products and their performance.

 

[ViperrepiV]

I am happy with my air, but i wouldn't mind a real explanation

 

[Anonymous Freak]

heh.

The capacity does seem a little low, I mean it theoretically should have at least CLOSE to 68 719 476 736 bytes of storage possible (Flash is memory like any other, manufactured in binary multiples, so that is 2^36.) Although 6% for parity might be about right. (Remember, flash memory isn't perfect, there are always a few bits here and there that are bad right out of the factory; and they reserve 'spare' bits for when more go bad later, along with for protecting against data going bad.)

As for 'usable space', I just installed Vista Ultimate x64 on a system with a 40 GB hard drive. After applying all the updates, I only had 16 GB of free space. That's just the OS. No iApps or anything. I flushed out all the update cache files, the hibernation file, etc; then installed Flight Simulator X and the Acceleration Pack. I now have too little empty hard drive space to re-create the hibernation file.

 

[whozurdaddy]

I think you guys are missing the pictures from Anand's review. Look at page 14. Note the model number of the drive is MCCOE64GEMPP. Now look at page 17. Compare his System Profiler screenshot to what you see in System Profiler.

I have yet to find the reason for this 4GB discrepancy.

 

[Beliyaal]

I got my Air today, and checked the drive size in Linux and it displays 60 billion bytes there as well.

I didn't find any good random write benchmark in Windows or OSX, so I guess I will just have to write one myself.

 

[Anonymous Freak]

I got my Air today, and checked the drive size in Linux and it displays 60 billion bytes there as well.

I didn't find any good random write benchmark in Windows or OSX, so I guess I will just have to write one myself.

Depends on your definition of "good"...

There's Xbench for OS X, which has a small random read/write part. And there are lots of 'heavy duty' benchmark programs for Windows that do as good of disk benchmarks as you can possibly imagine.

It's just too bad that the cross-platform GeekBench doesn't have a disk benchmark. It would be nice to see how different OSes handle disk access differently on the same hardware.

 

[dbell]

I think you guys are missing the pictures from Anand's review. Look at page 14. Note the model number of the drive is MCCOE64GEMPP. Now look at page 17. Compare his System Profiler screenshot to what you see in System Profiler.

I have yet to find the reason for this 4GB discrepancy.

That sure is strange. Mine says 55.9GB his 64GB after market Samsung Drive says 59.63, which is more in line with what I'd expect.

http://images.anandtech.com/reviews/mac/macbookair/review/SSDsize.jpg


at $15.60 a gig, I figure Apple owes each of us $62.44.

 

[Malcster]

I know this doesn't help much, but apple do now have a page saying the capacity is correct.. but as is apple's way on these things doesn't offer any explanation.

Link

 

[Beliyaal]

Ok, so I have created a program to measure random write performance, and the Air SSD is a slouch as expected.

First I tried the benchmark on my MacPro on a RAID-0 array with 3xRaptor 150GB drives:

Write IOP: 928.1 ops/sec Write Speed: 475198.9223 bytes/sec Average service time: 1.0774 ms
Read IOP: 178.7 ops/sec Read Speed: 91499.2862 bytes/sec Average service time: 5.5957 ms


The MacBook Air SSD is not the slowest by SSD standards, but it's not very fast:

Write IOP: 35.9 ops/sec Write Speed: 18361.3035 bytes/sec Average service time: 27.8847 ms
Read IOP: 3146.7 ops/sec Read Speed: 1611094.5523 bytes/sec Average service time: 0.3178 ms


I also tested my Corsair Flash Voyager 32 GB and got an explanation why it was so slow when I tried to run Vista from it (took maybe an half hour to boot):

Write IOP: 2.1 ops/sec Write Speed: 1079.2030 bytes/sec Average service time: 474.4242 ms
Read IOP: 1286.5 ops/sec Read Speed: 658698.9979 bytes/sec Average service time: 0.7773 ms


These results confirms that the 4 missing GB:s is not used to increase random write performance. I think Apple is in real trouble here.

The new Mtron drive should be much faster judging by their old drives that can do 110 randorm write IOP:s per second. 120 MB/sec read speed and 100 MB/sec write speed isn't bad either.

 

[whozurdaddy]

Good info once again Beliyaal. Thanks.

 

[alpinadvl]

at $15.60 a gig, I figure Apple owes each of us $62.44.

I hate to say this, because I hate lawsuits - but I really feel Apple is responsible for this - this is clearly false advertising. Even the benchmarks for the SSD are "plus / minus" - there is no "obvious" winner in terms of speed between the two.

I would rather have the correct drive given to me from the onset - as advertised / promised - than this stop gap, pricey model.

Other than this I am satisfied with the MBA (I dont regret it) - but if all these reviews were clearer, including the available capacity - I would have reconsidered the drive for sure. (And no, I cannot return it anymore)

-alf

 

[PelleB]

Apple fix to problem?

It sounds like certain MBA's have a problem in the way they were formatted from the factory.

Some MacBook Air computers may show hard disk drive (HDD) and Solid State Drive (SSD) capacity below expected levels. When using the MacBook Air for the first time, customers may see a disk full error message or an HDD/SSD capacity that is lower than normal.

http://docs.info.apple.com/article.html?artnum=307479

The fix mentioned in the link is to boot up from installation disks and reformat.

Can anyone confirm if this indeed fixes the problem and brings the capacity up to 60GB.