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SSD performance on iMac/RiMac?

M

MMcCraryNJ

macrumors 6502
Original poster
Oct 18, 2012
272
50
So, a question...

Does the iMac/Retina iMac have PCIe-based flash storage, or typical SATA III SSD?

I've assumed it was PCIe (offering the same performance as the nMP and rMBP). However, while both the nMP and rMBP clearly say "PCIe-based flash storage" on their respective spec listings (and on the Apple Store while configuring both machines), both iMac models simply say "SSD Storage".

I've seen teardowns of the iMac and it doesn't seem to include a typical 2.5 SSD drive, however the thought occurred to me that the flash storage could be still be SATA 3 based in the blade form factor.

Anyone have any insight? If it is truly is PCIe-based, why would Apple's own tech specs not point this out?
 
It's PCI-e SSD storage. However, it appears that (like the rMBP) the smaller SSDs only have two-channel access and are therefore getting around 700 Mbps read/write times, but it's possible (nay almost likely) that the 1Tb SSD is the same one used in the rMBP and running faster, more like 1000Mbps.

I'd like to see confirmation of this. Haven't seen a disk speed benchmark of a 1Tb SSD yet.

The Fusion drives are a combination, so are on 700 read and 300 write, as you would expect.
 
tillsbury said:
It's PCI-e SSD storage. However, it appears that (like the rMBP) the smaller SSDs only have two-channel access and are therefore getting around 700 Mbps read/write times, but it's possible (nay almost likely) that the 1Tb SSD is the same one used in the rMBP and running faster, more like 1000Mbps.

I'd like to see confirmation of this. Haven't seen a disk speed benchmark of a 1Tb SSD yet.

The Fusion drives are a combination, so are on 700 read and 300 write, as you would expect.
Click to expand...

I am really looking for some hard data on this as well. Which is hard to do because it is a fact that Apple could change up their tune at anytime without informing us. Not super likely, but it does happen. You know, the "One day a Samsung" and the "next day a SanDisk" dance. That type of thing makes a big difference to me.

There is no point for me for getting the 1TB unless it is substantially faster. I would prefer the 512GB as it is cheaper.

I guess we just need to keep an eye on these type of threads. The answer will come soon.
 
tillsbury said:
It's PCI-e SSD storage. However, it appears that (like the rMBP) the smaller SSDs only have two-channel access and are therefore getting around 700 Mbps read/write times, but it's possible (nay almost likely) that the 1Tb SSD is the same one used in the rMBP and running faster, more like 1000Mbps.

I'd like to see confirmation of this. Haven't seen a disk speed benchmark of a 1Tb SSD yet.

The Fusion drives are a combination, so are on 700 read and 300 write, as you would expect.
Click to expand...

unfortunately I don't remember in which thread it was, but there is already a benchmark of the 1.0 TB PCIe SSD (make SAMSUNG) in the Retina iMac. read/write are about 700 MB/Sec and it's connected using only two PCIe lanes. this fact made me cancel my order...
 
mikeboss said:
unfortunately I don't remember in which thread it was, but there is already a benchmark of the 1.0 TB PCIe SSD (make SAMSUNG) in the Retina iMac. read/write are about 700 MB/Sec and it's connected using only two PCIe lanes. this fact made me cancel my order...
Click to expand...

Could you find that please? The only ones I've seen have been 256 and 512gb.
 
mikeboss said:
unfortunately I don't remember in which thread it was, but there is already a benchmark of the 1.0 TB PCIe SSD (make SAMSUNG) in the Retina iMac. read/write are about 700 MB/Sec and it's connected using only two PCIe lanes. this fact made me cancel my order...
Click to expand...
Early reports suggest that the iMac, unlike the MBP, only has a 2-lane PCIe connector, and is unable to take full advantage of 4-lane SSDs like the Samsung.

This led me to cancel my iMac Retina order. If I spend $3000 or more on a computer, I expect to use it for at least 4-5 years. I don't want a computer that is limited to 700 Mbps one-year from now, much less five years from now. A 4-lane PCIe interface can support up to 3200 Mbps, and Samsung has already announced a new 4-lane PCIe SSD that delivers upwards of 1400 Mbps. A year from now, there will be 4-lane PCIe SSD drives that deliver 2000-2500Mbps. However, all of these drives would be useless in an iMac that has a hard-wired 2-lane PCIe interface.

Why does this matter? Because I/O is still the main bottleneck in current computers.
 
Last edited:
Come on then, who out there bought a maxed-out riMac and can run a quick disk benchmark for us? Mine is on a plane somewhere between here and Pudong...
 
hyune83 said:
Would it even matter though as the ssd is non-user replaceable?
Click to expand...

You can't do anything about it, but it's interesting to know. The rMBP has this issue: the smaller SSDs are slower than the 1Tb. I'm trying to find out whether the iMac is the same. It might help potential buyers decide whether the SSD upgrade is relevant for them.
 
This is why I went for a 512GB SSD in my retina iMac., because:

1. I can't notice any difference between the 512GB in my 13" rMBP and 1TB 4-lane in my 15" rMBP.

2. It's cheaper, and I don't need a massive amount of internal storage.
 
Not a deal breaker to me (I'm still doing totally fine with a spinning HDD), but that is really annoying.
 
KenAFSPC said:
Early reports suggest that the iMac, unlike the MBP, only has a 2-lane PCIe connector, and is unable to take full advantage of 4-lane SSDs like the Samsung.

This led me to cancel my iMac Retina order. If I spend $3000 or more on a computer, I expect to use it for at least 4-5 years. I don't want a computer that is limited to 700 Mbps one-year from now, much less five years from now. A 4-lane PCIe interface can support up to 3200 Mbps, and Samsung has already announced a new 4-lane PCIe SSD that delivers upwards of 1400 Mbps. A year from now, there will be 4-lane PCIe SSD drives that deliver 2000-2500Mbps. However, all of these drives would be useless in an iMac that has a hard-wired 2-lane PCIe interface.

Why does this matter? Because I/O is still the main bottleneck in current computers.
Click to expand...

Ok, but there's never been a new computer built that wasn't deficient in some way or another. I'd suggest if maximum through-put/performance is that critical for you, a non-upgradable all-in-one box is not going to be your best choice.
 
Yeah, it seems pretty harsh to cancel an order just bc the internal SSD is not completely cutting edge speed-wise. Would you even notice the difference between 10,000 and 750 MB/s speeds?
 
Melodeath said:
Yeah, it seems pretty harsh to cancel an order just bc the internal SSD is not completely cutting edge speed-wise. Would you even notice the difference between 10,000 and 750 MB/s speeds?
Click to expand...

no, I don't think that cancelling my order was too harsh. first reason is because I now run an Apple PCIe SSD in my classic Mac Pro (4 lanes, gives about 1200 MB/Sec) and I do not want to go backwards performancewise. second reason: Apple charges premium dollars (800.00) for a 1.0 TB SSD while a standard SAMSUNG 1.0 TB SSD costs roughly half. for this kind of money I think I'm entitled to get cutting-edge hardware.
 
KenAFSPC said:
Early reports suggest that the iMac, unlike the MBP, only has a 2-lane PCIe connector, and is unable to take full advantage of 4-lane SSDs like the Samsung.

This led me to cancel my iMac Retina order. If I spend $3000 or more on a computer, I expect to use it for at least 4-5 years. I don't want a computer that is limited to 700 Mbps one-year from now, much less five years from now. A 4-lane PCIe interface can support up to 3200 Mbps, and Samsung has already announced a new 4-lane PCIe SSD that delivers upwards of 1400 Mbps. A year from now, there will be 4-lane PCIe SSD drives that deliver 2000-2500Mbps. However, all of these drives would be useless in an iMac that has a hard-wired 2-lane PCIe interface.

Why does this matter? Because I/O is still the main bottleneck in current computers.
Click to expand...

I completely agree. What a stupid move on Apple's part. This is also holding me back from a purchase.

----------
Melodeath said:
Not a deal breaker to me (I'm still doing totally fine with a spinning HDD), but that is really annoying.
Click to expand...

Spinners do not belong in a computer anymore for any reason. Sorry, but true.
 
BTW: it's possible that there's a technical reason for this (PCIe SSD using only two lanes). maybe there are just not enough PCIe lanes with this type of CPU... according to http://ark.intel.com the 4.0 GHz processor only has 16 lanes..!?
 
And my late 2009 iMac is getting 110Mb/sec. So I would be happy with a Fusion drive . . . but I did get the SSD instead.
Next week can't come too soon!
 
Cape Dave said:
Spinners do not belong in a computer anymore for any reason. Sorry, but true.
Click to expand...

I don't see why. I do professional audio work using spinning hard drives. Sure, I wish they were SSD, but the price is still too high in terms of cost/size ratio.
 
yjchua95 said:
This is why I went for a 512GB SSD in my retina iMac., because:

1. I can't notice any difference between the 512GB in my 13" rMBP and 1TB 4-lane in my 15" rMBP.

2. It's cheaper, and I don't need a massive amount of internal storage.
Click to expand...

Of course you won't. :) Thank you for putting some real world perspective into this discussion.

The only way to notice the differences between these "fast" SSDs and "slow" SSDs is to run artificial benchmarks, or copy terabytes of data 24 hours a day. You would be hard pressed to find a normal workflow that would expose the shortcomings of the "slow" SSD.
 
yeah, and "640 K ought to be enough for anybody". I work with computers for a living since 25 years and there's only one thing I really hate about working with them: staring at progress bars. 700MB/Sec or 1200MB/Sec is a substantial difference. sure, most users won't notice this. I will, period.
 
mikeboss said:
yeah, and "640 K ought to be enough for anybody". I work with computers for a living since 25 years and there's only one thing I really hate about working with them: staring at progress bars. 700MB/Sec or 1200MB/Sec is a substantial difference. sure, most users won't notice this. I will, period.
Click to expand...

The only time I notice it is when working on heavy 4K work.

Which isn't all that often.
 
KenAFSPC said:
...This led me to cancel my iMac Retina order. If I spend $3000 or more on a computer, I expect to use it for at least 4-5 years. I don't want a computer that is limited to 700 Mbps one-year from now, much less five years from now. A 4-lane PCIe interface can support up to 3200 Mbps, and Samsung has already announced a new 4-lane PCIe SSD that delivers upwards of 1400 Mbps. A year from now, there will be 4-lane PCIe SSD drives that deliver 2000-2500Mbps. However, all of these drives would be useless in an iMac that has a hard-wired 2-lane PCIe interface.

Why does this matter? Because I/O is still the main bottleneck in current computers.
Click to expand...

I agree that I/O is still a bottleneck in computers, but 700 Mbps will not be outdated one year from now or even in 4-5 years for that matter. Yes, if you're editing multi-cam 1080p or multi-cam 4K, then you certainly need all the throughput your data can get. But if that's the case, a 5K iMac without external storage is not the setup you would use anyway. You simply need to buy an external box and setup a RAID to get the speed you desire.

The idea of not using a 5K iMac just because it only uses two lanes instead of four seems kind of silly/pointless to me, but hey, your needs are most definitely different than mine and that's cool too.

Bryan
 
mikeboss said:
yeah, and "640 K ought to be enough for anybody". I work with computers for a living since 25 years and there's only one thing I really hate about working with them: staring at progress bars. 700MB/Sec or 1200MB/Sec is a substantial difference. sure, most users won't notice this. I will, period.
Click to expand...

I too work with computers for a living and have been doing it for a long time, so I am curious what it is that you do that makes you believe you will notice a difference between an SSD that is capable of sequential reads/writes of 1000 MB/s and one that is capable of 700 MB/s?

For such a specialised workflow I would consider multiple SSDs in RAID 0 in a Thunderbolt 2 enclosure, or get a Lacie Little Big Disk Thunderbolt 2, at least.

I measured just under 1400MB/s in sequential read speed to the array and a little over 1100MB/s in writes.
Click to expand...

http://www.anandtech.com/show/7618/lacie-little-big-disk-thunderbolt-2-mini-review


Maybe even consider a more specialised enterprise solution, of which many are available.

----------
Bryan Bowler said:
I agree that I/O is still a bottleneck in computers, but 700 Mbps will not be outdated one year from now or even in 4-5 years for that matter. Yes, if you're editing multi-cam 1080p or multi-cam 4K, then you certainly need all the throughput your data can get. But if that's the case, a 5K iMac without external storage is not the setup you would use anyway. You simply need to buy an external box and setup a RAID to get the speed you desire.

The idea of not using a 5K iMac just because it only uses two lanes instead of four seems kind of silly/pointless to me, but hey, your needs are most definitely different than mine and that's cool too.

Bryan
Click to expand...

I couldn't agree more, except for the use of mega bits per second in your post. :)
 
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