Which iMac 27 to buy?

[varian55zx]

Well, one can only hope

No, clearly this forum needs my wealth of knowledge on fusion drive or else many would have been misleaded... I know I have saved many people hundreds of $!!

Fusion is fine, I even recommend it and will continue to do so... it's cost effective and works very well. It is fast when compared to a standalone HDD. Night and day difference and for anyone trying to save, they should strongly consider the 2tb or 3tb fusion options. However they should not consider the 1tb option. In my opinion.

If you want to know why I personally prefer pure flash (I went with the 512 and the performance is just off the charts), then read my post a couple posts up

 

[rbart]

This argument doesn't make any sense.

I am the owner of a great media library.

If I get a new, say, movie file. 3 gb file or so, HD movie. I know I don't want any of that on the SSD. Who knows when I will actually watch it, and when I do, I don't benefit from having it on the SSD. It would just be a waste of space.

If I had a fusion drive I would drag it to the fusion drive, and it's anyone's guess which drive those 3gb of data will move to. It will probably stay on the SSD for a long time (fusion is slow to move files off the SSD), and part of it may never move off the SSD, ever.

Possibly the most concerning part is there is no way to determine what is on the SSD and what is on the HDD. Nothing. zero. You can never know what is where. Why? Because fusion is designed for Grandmas and elementary students who don't desire any level of customization with their machines.

Of course with my setup I can just drag the whole file to the HDD and be done with it.

If you are unable to understand what I have mentioned in this post I am done with you. I'm finished. The advantages of having a split drive are just so obvious, and if you still don't understand them by now, I just don't know what to say

In this case, you big media file never stay on the FD.
You just have 4Gb of write cache.
Your file arrives ont the SSD part and is quickly moved to the HDD part. It's very easy to monitorFD activity with an "iostat" command.
It has been tested by a lot of people, it works well for every one like that but you continue to tell the contrary...

 

[varian55zx]

In this case, you big media file never stay on the FD.
You just have 4Gb of write cache.
Your file arrives ont the SSD part and is quickly moved to the HDD part. It's very easy to monitorFD activity with an "iostat" command.
It has been tested by a lot of people, it works well for every one like that but you continue to tell the contrary...

I tell the truth

I disagree with your sentiment that it is moved to the HDD quickly. In my experience it does the opposite. This is one of my primary complaints about fusion drive, if you must know

There is 4gb of write cache, true, even high quality HD films don't exceed 4gb, so it will go to the SSD first. Everything goes to the SSD first in fusion drive (another flaw). If the SSD portion is completely filled when I complete my import something will be moved off the HDD- I can tell you it won't be all of the movie. I hope this is hitting home, rbart

 

[rbart]

You are completely wrong.
It's very easy to notice this beahviour with iostat.
TH FD always keep 4Gb free.
Once you have put a 3Gb file in this space, it will be moved to the HDD.
It's a good thing for performance to always write first on SSD.
On the SSD, you only keep the blocks (part of the files) that are statisticly used most of the time.
For example, if you have a big Photos library, most of the data blocks stay on the HDD, but the index can be located on the SSD. It's impossible to optimize this with separate drives.

 

[varian55zx]

You are completely wrong.
It's very easy to notice this beahviour with iostat.
TH FD always keep 4Gb free.
Once you have put a 3Gb file in this space, it will be moved to the HDD.
It's a good thing for performance to always write first on SSD.
On the SSD, you only keep the blocks (part of the files) that are statisticly used most of the time.
For example, if you have a big Photos library, most of the data blocks stay on the HDD, but the index can be located on the SSD. It's impossible to optimize this with separate drives.

You're just making stuff up now.

Maybe you don't like the way the argument is being presented... stick to the information buddy

Have a read of this article and you will see it all goes to the SSD first. It's also impossible to predict what goes where and it is impossible to determine what is on the HDD and what is on the SSD. Manually trying to get fusion to move things to the HDD is a pain, and it doesn't work. I've tried it because I actually owned one!

http://www.anandtech.com/show/6679/a-month-with-apples-fusion-drive/5

 

[mpe]

If there is one scenario where the fusion works particularly well it is photo processing in sw like Lightroom.

The post above saying that fusion is slow in that situation is completely false.

The reason why ssd is superior to hdd isn't so much its high sequential transfer speeds but more importanly i/o latencies (especially writes and blocking io. The FD, being a caching solution combining both 128GB SSD and 7200rpm hdd is doing a great job at hiding latencies and won't be slowing you down in Lightroom.

Nevermind, while the FD is fine for image processing, I/O speed isn't that important for lightroom anyway:

https://www.pugetsystems.com/labs/articles/Adobe-Lightroom-2015-8-Storage-Performance-Analysis-875/

 

[maflynn]

The post above saying that fusion is slow in that situation is completely false.

I disagree, Lightroom is one instance where I see it being adversely affected by the spinning HD. It takes longer for my to scroll through my images and then render the preview.

 

[fathergll]

I've owned a 1TB Fusion(128GB+1TB HD) iMac for 2 years now. My opinion is that the advantages of a pure SSD are easily enough to warrant buying it over the larger Fusion drive.

Opening and previewing large RAW files from my 36mp Pentax K1 isn't fun when using a fusion drive.(the pixelshift RAW files are 150mb a photo) Add on once you make the decision to go fusion drive you basically made the decision that you're not going to ever use bootcamp(there are countless threads about how difficult it is to bootcamp with a fusion drive.)

External SSDs are so tiny and fast I wouldn't hesitate using one in addition to an SSD.

 

[mpe]

I disagree, Lightroom is one instance where I see it being adversely affected by the spinning HD. It takes longer for my to scroll through my images and then render the preview.

Just to be clear. I don't recommend spinning hd to anyone. Fusion is a completely different thing.

Lightroom doesn't render previews live. That would be too slow. Lr itself is quite slow, but that's a different story.

Since the fastest quad-core cpu can decode roughly 1-2 images per sec. it doesn't really matter if peak sequential speed of the master storage is 150MB/s or 3500MB/s.

The previews are normally generated on import and persisted as part of catalogue. Previews are small and easily prefetched or cached during browsing.

Anyway, see the linked article for performance analysis of lr.

 

[Glockworkorange]

I'm looking to get the iMac retina 27 inch. I don't know which hard drive to get. Should I get 1TB Fusion, 2TB Fusion, 3TBFusion or 256GB of flash?

I want a FAST computer, I don't want to have to wait when using the web or editing photos in light room. I don't edit lots of photo's but when I do I don't want to wait.

I use my computer for surfing the web, editing photos every now and then. I also use Microsoft word and excel allot.

I have always purchased cheap $500-$600 computers and they all last a couple months then get slower and slower.

What are your suggestions?

What's your budget? Money not an issue? As much flash as offered and external drives on TB2.

If you're on a budget, pure 256 SSD or the 2 TB HD/128 SSD fusion option. Stay away from the 1 TB fusion, because the SSD portion is like 24 G.

OR....the 2014 1 TB fusion option is great, because you get the 128 SSD and the 1 TB hard drive. Probably can get them a little cheaper. This is the model I have. Plenty fast enough, although I don't edits lots of pictures and videos outside of Photos.
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I've owned a 1TB Fusion(128GB+1TB HD) iMac for 2 years now. My opinion is that the advantages of a pure SSD are easily enough to warrant buying it over the larger Fusion drive.

Opening and previewing large RAW files from my 36mp Pentax K1 isn't fun when using a fusion drive.(the pixelshift RAW files are 150mb a photo) Add on once you make the decision to go fusion drive you basically made the decision that you're not going to ever use bootcamp(there are countless threads about how difficult it is to bootcamp with a fusion drive.)

External SSDs are so tiny and fast I wouldn't hesitate using one in addition to an SSD.

True that Bootcamp or most other kinds of partitioning are better left for SSD's. For more casual users, fusion is fine.

 

[MrNomNoms]

Go for a pure SSD solution - 512GB; my configuration I have a 512GB SSD drive with a 1TB external drive with a Sandisk X400 SSD inside it. I'd simply go for a SSD simply because you're buying a sealed unit and if you want to make life easier for yourself then reduce the number of moving parts with the hard disk more likely to die long term than any of the other parts especially if you're going to really push the system in terms of work load.

 

[varian55zx]

Go for a pure SSD solution - 512GB; my configuration I have a 512GB SSD drive with a 1TB external drive with a Sandisk X400 SSD inside it. I'd simply go for a SSD simply because you're buying a sealed unit and if you want to make life easier for yourself then reduce the number of moving parts with the hard disk more likely to die long term than any of the other parts especially if you're going to really push the system in terms of work load.

I agree with this. I, like you, opted for the 512 option and I have absolutely never looked back.

It feels good to know I don't have spinning metal in my beautiful iMac, makes me feel like my computer is more up to date.

I'm going to be buying a 2tb external SSD soon though the experience with my external HDDs, really, has been completely fine.

 

[MrNomNoms]

I agree with this. I, like you, opted for the 512 option and I have absolutely never looked back.

It feels good to know I don't have spinning metal in my beautiful iMac, makes me feel like my computer is more up to date.

I'm going to be buying a 2tb external SSD soon though the experience with my external HDDs, really, has been completely fine.

What will be interesting to see what the performance is like once APFS comes out of beta and will be ready for prime time in 10.13. I'll do a clean install rather than conversion so it'll be greta to also to see how native file system features such as snapshots are used for 'time machine' rather than the mess of abstraction, work arounds and hacks to provide said features.

 

[maflynn]

Go for a pure SSD solution - 512GB;

If you can afford the cost, definitely. The SSD is the best option, for my case, I needed more then 512GB of storage so the Fusion drive made more sense.

 

[willmtaylor]

If you can afford the cost, definitely. The SSD is the best option, for my case, I needed more then 512GB of storage so the Fusion drive made more sense.

As the GPU on my 2009 iMac just bit the dust, this will most likely be my situation as well.

I'll most likely be getting the 2TB version.

 

[MrNomNoms]

If you can afford the cost, definitely. The SSD is the best option, for my case, I needed more then 512GB of storage so the Fusion drive made more sense.

Why not have a 512GB SSD as your scratch disk and then have an external drive for stuff you aren't working on so then it free's up space?

 

[maflynn]

Why not have a 512GB SSD as your scratch disk and then have an external drive for stuff you aren't working on so then it free's up space?

I could and I thought about that to be honest, but I was already dealing with that with my MBP and I felt a single drive solution was better then having my data spread across an internal drive and external. I know your suggestion was (and is) perfectly valid but for me, I just didn't want to deal with that. Something about having everything on a single volume appeals to me.

 

[v1597psh]

I think the most cost saving option for you will be going with standard 1TB hard drive and buying an external USB 3 UASP SSD drive. That's what I've done. I run the OS right from external SSD and it works perfectly + I have a hard drive for all my files. I would go with Apple SSD if they were standard SATA and not PCIe, which are much more expensive as I don't need those speeds.

 

[hfg]

One advantage of having all your "stuff" on an external drive is if you need to send it to the repair shop for some reason ... you unplug your sensitive and personal data and leave it at home on your desk, safe from the eyes of the repair tech.

Have a fast SSD internal for OS X and applications .... and a larger fast external SSD for your data.