Once and for all, do larger SSDs require more RAM?

[Kal-037]

so I know many have said the 1TB Pro doesn’t use the extra RAM for memory management... I’m curious if that is the case with Apple’s storage type. I also ask because I have heard way more people say it is absolutely for storage management while many also say it is not.
I wish Apple would have said why, lol.
*also not trying to start a war, so let’s keep this civil. I’m just curious of who thinks what.





Kallum.

 

[UltimateSyn]

AFAIK it’s about 1MB of RAM to index every GB of storage (I have not proven these numbers myself, just read them multiple times). So in theory the 1TB iPad actually gives you 1.5GB more of usable RAM over the 512GB version.

 

[ericwn]

I’m interested in seeing some data points or research rather than another MR opinion festival.

 

[AutomaticApple]

*also not trying to start a war, so let’s keep this civil. I’m just curious of who thinks what.

A civil MacRumors user?

 

[rui no onna]

I’m interested in seeing some data points or research rather than another MR opinion festival.

As none of us are privy to the details of the storage controller in Apple's chipsets, all we can make are educated guesses. Storage performance on the 2018 iPad Pros doesn't suggest DRAMless. The design of the chipset allows CPU, GPU and storage to share RAM. Apart from being fast/efficient, not needing to dedicate/reserve resources to just one task is beneficial for users as memory can be allocated to whatever needs it.

https://www.tomshardware.com/reviews/dramless-ssd-roundup,4833.html

Mind, 1MB per 1GB is what Samsung, Crucial, etc. use in their SSDs. The SSDs shouldn't need it majority of the time but it would help during periods of heavy load (in terms of IOPS, not throughput).

https://www.anandtech.com/show/12408/the-samsung-860-evo-m2-2tb-ssd-review

 

[tps3443]

AFAIK it’s about 1MB of RAM to index every GB of storage (I have not proven these numbers myself, just read them multiple times). So in theory the 1TB iPad actually gives you 1.5GB more of usable RAM over the 512GB version.

That’s not true. The 512GB has 3.69Gb of ram, and the 1TB has 5.6GB of ram. So it’s still like 1,950MB more ram no matter how you slice it.
[doublepost=1556383083][/doublepost]

so I know many have said the 1TB Pro doesn’t use the extra RAM for memory management... I’m curious if that is the case with Apple’s storage type. I also ask because I have heard way more people say it is absolutely for storage management while many also say it is not.
I wish Apple would have said why, lol.
*also not trying to start a war, so let’s keep this civil. I’m just curious of who thinks what.





Kallum.

The rumor started before these iPads were even released. Someone made it up to rationalize why they shouldn’t buy a 1TB iPad Pro lol? I have no idea. And this is what everyone believed.

Other than reserved ram which all iPads have some of there ram reserved no matter if it is a 64GB or a 512GB or even the 1TB model. The 512GB has 92% of the 4GB available to the operating system, and the 1TB iPads have 93% of there 6GB available to the operating system. And all of this ram can be used for active application, inactive applications, free ram, and wired memory.

I’ve loaded a 1TB iPad Pro to nearly full with copies of this exact same large file. It was in excess of 915GB of storage and memory utilization stayed the same, within less than 1% whether it was empty or full.

The same goes for the 512GB iPad Pro too, it was within 1% of the same amount of memory utilized whether it was full or empty.

Both iPad Pro 11” models were running on identical backups.

Also, the 512GB and lower tier units actually use a higher percentage of its ram for resources than the 1TB model does.
[doublepost=1556383462][/doublepost]

I’m interested in seeing some data points or research rather than another MR opinion festival.

I’ve got tons of data on this. What would you like to see? I’ve tested a 512GB 11”, vs a 1TB 11” probably between 30-40 hours lol. Memory utilization, on the same backups, then loading internal storage and repeating this process by testing various applications. I was making a video, but I’m just way to busy to finish. And I had to give the 512GB 11” Pro back to my brother lol.

The 1TB has parallelism on its internal storage too. So, instead of a single storage chip soldered on. There are (2) 512GB chips soldered side by side. Parallelism results in much faster read/write speeds on the 1TB model.

Regardless, your always sitting ahead with the 6GB of ram. It is 6GB of ram, it is not used for storage. It is used for applications, or whatever people may use there ram for on there iPad.

I guess what I’m getting at is, the 4GB iPad Pro memory is managed the same way as a 6GB iPad Pro. Although, certain professional applications are programmed to take advantage of this, being able to add extreme mounts of layers in drawing, or editing apps and things like the 4GB ram models “are not allowed to do” Other than that your just going to have more free ram available. And or more inactive applications that do not need to constantly reload.

 

[rui no onna]

I’ve loaded a 1TB iPad Pro to nearly full with copies of this exact same large file. It was in excess of 915GB of storage and memory utilization stayed the same, within less than 1% whether it was empty or full.

The same goes for the 512GB iPad Pro too, it was within 1% of the same amount of memory utilized whether it was full or empty.

Both iPad Pro 11” models were running on identical backups.

Also, the 512GB and lower tier units actually use a higher percentage of its ram for resources than the 1TB model does.

That's expected behavior with static and sequential data, though. We need something like AnandTech's performance consistency test (continuous random 4K write) for objective comparison.

I expect the 1TB was designed to work well even in extreme edge cases (e.g., random small block write heavy workload while wear leveling). If you're just putting both through the same workload (read/write), it stands to reason active RAM usage is the same.

 

[tps3443]

That's expected behavior with static and sequential data, though. We need something like AnandTech's performance consistency test (continuous random 4K write) for objective comparison.

I expect the 1TB was designed to work well even in extreme edge cases (e.g., random small block write heavy workload while wear leveling). If you're just putting both through the same workload (read/write), it stands to reason active RAM usage is the same.

There’s not many detailed benchmarks on iOS, or even any good ram monitoring apps for that matter. Definitely no good SSD testing applications either.

 

[rui no onna]

There’s not many detailed benchmarks on iOS, or even any good ram monitoring apps for that matter. Definitely no good SSD testing applications either.

I know, which is unfortunate. Hence, all we have are educated guesses based on general SSD knowledge and performance.

 

[tps3443]

4GB of ram was introduced in 2015 with the very first iPad Pro “12.9 only”. Honestly looking at us now, nearly half way through 2019 and we only have 6GB of ram on the most expensive iPad?!

I imagine back in 2015 that 4GB was way more overkill than 6GB is now.

Why did they decide to only use 2GB in the 9.7” model that was released in 2016?

Seems odd to me..

So, in other words the original iPad Pro 12.9 is still a tank lol.

 

[rui no onna]

4GB of ram was introduced in 2015 with the very first iPad Pro “12.9 only”. Honestly looking at us now, nearly half way through 2019 and we only have 6GB of ram on the most expensive iPad?!

I imagine back in 2015 that 4GB was way more overkill than 6GB is now.

Why did they decide to only use 2GB in the 9.7” model that was released in 2016?

Apple has always been stingy with RAM. They tend to put the lowest amount they can get away with.

The 9.7 didn't *need* the RAM as much as the 12.9. The Pro 12.9 has 5.6 million pixels compared to the Pro 9.7 which only has 3.1 million pixels. I imagine a task like gaming on the 2015 Pro 12.9 would be pretty poor if Apple only put 3-4GB in it. All things considered, the Pro 9.7 still performs quite well despite its limited RAM.

 

[tps3443]

Apple has always been stingy with RAM. They tend to put the lowest amount they can get away with.

The 9.7 didn't *need* the RAM as much as the 12.9. The Pro 12.9 has 5.6 million pixels compared to the Pro 9.7 which only has 3.1 million pixels. I imagine a task like gaming on the 2015 Pro 12.9 would be pretty poor if Apple only put 3-4GB in it. All things considered, the Pro 9.7 still performs quite well despite its limited RAM.

I was looking in to the new Samsung Galaxy S10+ “Ultimate Performance Edition”
It has 12GB of ram, and while this seems like a lot, it hammers ram usage. Mac OS, and iOS seem to get by with way less ram and manage it much better too.

I was watching someone open as many applications as they could on that S10+ 1TB and it was using easily 7-8+GB of ram with nothing even serious going on. Just a few random apps open like, Edmunds, cars.com, eBay, Reddit, several other apps are open etc.etc. I’m thinking the whole time, where is this ram going?! So, it really needs 12GB lol.

 

[rui no onna]

I was looking in to the new Samsung Galaxy S10+ “Ultimate Performance Edition”
It has 12GB of ram, and while this seems like a lot, it hammers ram usage. Mac OS, and iOS seem to get by with way less ram and manage it much better too.

I was watching someone open as many applications as they could on that S10+ 1TB and it was using easily 7-8+GB of ram with nothing even serious going on. Just a few random apps open like, Edmunds, cars.com, eBay, Reddit, several other apps are open etc.etc. I’m thinking the whole time, where is this ram going?! So, it really needs 12GB lol.

Unused RAM is wasted RAM. Makes sense to use excess RAM to cache frequently used stuff, preload webpages in the background, etc. to make things run faster.

 

[pshufd]

I’m interested in seeing some data points or research rather than another MR opinion festival.

I studied file systems back in the mid-1970s and I think that the operating system that I used at the time just used linked lists to maintain directories and it could get slow if there were a lot of files in a directory and if could take longer to traverse a file if it was very large. I would guess that an ISAM approach was eventually used on later operating systems. I'm pretty sure that something like that was used on the VAX/VMS file system.

I'm not sure what's used today - it might be a database or it might be traditional. But yeah, it will take more memory to cache file system indexing if the space to index is larger. I imagine looking for research papers on file systems would yield some technical papers on what the modern approach is. I had a former co-worker at Microsoft working on their journaling file system a few decades ago but that was more about ACID properties I think.

 

[rui no onna]

I studied file systems back in the mid-1970s and I think that the operating system that I used at the time just used linked lists to maintain directories and it could get slow if there were a lot of files in a directory and if could take longer to traverse a file if it was very large. I would guess that an ISAM approach was eventually used on later operating systems. I'm pretty sure that something like that was used on the VAX/VMS file system.

I'm not sure what's used today - it might be a database or it might be traditional. But yeah, it will take more memory to cache file system indexing if the space to index is larger. I imagine looking for research papers on file systems would yield some technical papers on what the modern approach is. I had a former co-worker at Microsoft working on their journaling file system a few decades ago but that was more about ACID properties I think.

You bring up an interesting point. We're not quite discussing filesystem RAM usage here (APFS is what Apple uses now which has some similarities to ZFS and BTRFS) but rather that of the storage controller. We forgot to take into account filesystem use. I know ZFS has pretty heavy RAM requirements.

NAND flash have limited P/E cycles before they become unusable. You want to avoid battering the same cells over and over hence the need for wear leveling. Because of this, block 123 as the OS/filesystem sees it might actually be physically located in block 12345. The logical-physical block address mapping table is one of the things that's usually cached in RAM. There are of course DRAMless SSDs or SSDs that have a very small amount of RAM which only cache part of the mapping table but there's a performance penalty for doing so.

Given Apple has control over both A12(X) storage controller and APFS though, it'll be quite interesting to learn about any integration between the two.

 

[boast]

This isn't my field, but interesting to think about.

In OS X and in earlier versions of iOS, the size of a page is 4 kilobytes. In later versions of iOS, A7- and A8-based systems expose 16-kilobyte pages to the 64-bit userspace backed by 4-kilobyte physical pages, while A9 systems expose 16-kilobyte pages backed by 16-kilobyte physical pages.

So would one think they increased the size of each page in order to maintain performance for accessing 1TB of disk space (reduce the higher chance of a page miss as disk space increases)? And that increased size requires a larger page table per process, thereby increasing total physical RAM usage?

I don't see any Apple documentation on how/if Table Lookaside Buffers would be placed in RAM and it's sizing relative to disk space.

I assume there is some relation to performance/memory of TLB and Page Table sizing relative to disk space available.

 

[tps3443]

This was a cool thread in regards to if more ram may or may not be more useful.

Obviously the 1TB/6GB is a niche product. Mainly because of the cost. Although, if there is a need then there is a option. Most people do not need more than 4GB of ram and iOS usually doesn’t either, and we are just now getting to a point where some developers are offering a benefit for it, and developing deeper creative capabilities based on RAM limitations. I think the iPad is headed toward more possibilities, especially with iOS13 around the corner.

I think it’s a exciting time to own a iPad. 6GB will just be the standard for “Pro iPads” next year, and Apple might offer a premium priced model with more ram possibly as high as 10-12GB.

https://forums.macrumors.com/thread...rom-more-than-4-gb-ram.2177443/#post-27274811

 

[secretk]

I was looking in to the new Samsung Galaxy S10+ “Ultimate Performance Edition”
It has 12GB of ram, and while this seems like a lot, it hammers ram usage. Mac OS, and iOS seem to get by with way less ram and manage it much better too.

I was watching someone open as many applications as they could on that S10+ 1TB and it was using easily 7-8+GB of ram with nothing even serious going on. Just a few random apps open like, Edmunds, cars.com, eBay, Reddit, several other apps are open etc.etc. I’m thinking the whole time, where is this ram going?! So, it really needs 12GB lol.

I have different experience. I actually hate the way iOS handles RAM. Reloading tabs and apps constantly is something iOS does to keep the devices with less RAM. If that is OK for you sure. It is not acceptable for me. Reloading an app every 15 minutes hinders my productivity. I personally associate this with bad user experience and lagging. Constant reloads for me is a sign for a slow and inefficient device. And this is what I feel when using iOS device.

With my Android phone I could leave open tabs in the browser for a day and they would not reload. And when they do reload, the reload is quite faster than on the iPhone. It creates far better user experience.

Same for apps. I could leave an open tab for a day on my Android phone and I could pick up from where I left. In the cases where it has to be reloaded, it is faster. I almost do not see the reload. With iOS I could always see the reload and it slows me down.

 

[tps3443]

I have different experience. I actually hate the way iOS handles RAM. Reloading tabs and apps constantly is something iOS does to keep the devices with less RAM. If that is OK for you sure. It is not acceptable for me. Reloading an app every 15 minutes hinders my productivity. I personally associate this with bad user experience and lagging. Constant reloads for me is a sign for a slow and inefficient device. And this is what I feel when using iOS device.

With my Android phone I could leave open tabs in the browser for a day and they would not reload. And when they do reload, the reload is quite faster than on the iPhone. It creates far better user experience.

Same for apps. I could leave an open tab for a day on my Android phone and I could pick up from where I left. In the cases where it has to be reloaded, it is faster. I almost do not see the reload. With iOS I could always see the reload and it slows me down.

He was testing the Samsung Galaxy S10 with 12GB of ram against a iPhone XS with 4GB of ram. Actually the iPhone kept things open longer. As he cycled back through every app he had originally opened, or webpage. The iPhone was keeping the apps open, and didn’t require a reload. The Samsung was reloading a lot of the apps and pages again.

Some apps require a reload regardless though.. It’s the smart thing to do. It has nothing to do with just memory all the time, you could open an app and it is using 12% CPU usage while idle. So, that’s a little high for background usage and would surely waste battery and resources, if you just minimized it, it would be much smarter to stall that app and force a reload Upon relaunch.

Anyways, I’ll try to find the video again and post it on here. The iPhone definitely was able to maintain more apps without requiring a reload. I’m not biased. And I really like the Galaxy S10 1TB specifically. I was considering buying one. I just thought that was interesting.

 

[secretk]

He was testing the Samsung Galaxy S10 with 12GB of ram against a iPhone XS with 4GB of ram. Actually the iPhone kept things open longer. As he cycled back through every app he had originally opened, or webpage. The iPhone was keeping the apps open, and didn’t require a reload. The Samsung was reloading a lot of the apps and pages again.

Maybe it depends on the actual Android phone. I have Android phone with 4 GB RAM and iPhone with 2 GB RAM. The Android phone is miles ahead of the iPhone when it comes to RAM management. My Android phone makes sure to never use more than 2 GB or RAM. It loads everything fast and its battery lasts days.

It also depends on whether you count the iOS animations themselves. I know people like them and consider them part of the smooth experience. I hate them. They are just gimmick to try to distract me from reloading. I have never experienced iOS device that does not reload apps. So I do consider animations when I measure reloading because it is reloading actually.

Some apps require a reload regardless though.. It’s the smart thing to do. It has nothing to do with just memory all the time, you could open an app and it is using 12% CPU usage while idle. So, that’s a little high for background usage and would surely waste battery and resources, if you just minimized it, it would be much smarter to stall that app and force a reload Upon relaunch.

I disagree. That is iPhone problem because it does not have enough battery. It is again that idea of Apple to choose looks over functionality. I do not need that thin phone. I need good battery life and here again my Android phone wins. On top of it iOS devices have powerful CPUs that I do not even use to their full potential. RAM however is never enough for my usage. It just does not make sense and for me as a user that is one factor to not consider paying a lot for iOS device. I do not need that powerful CPU. I need more RAM. Why would I need CPU that I do not use more than 12 % of but would have just 4 GB RAM that I use all the time as I have on average 50 apps open and at least 30 to 35 tabs open? I need to have both powerful CPU and good enough RAM and 4 GB is not.

And I am not talking about games where I understand the need for reloading. I am talking about simple apps like Notes, Files, chat clients etc. Those apps do not require that much CPU to be reloaded every 10/15 minutes (sometimes even more).

Anyways, I’ll try to find the video again and post it on here. The iPhone definitely was able to maintain more apps without requiring a reload. I’m not biased. And I really like the Galaxy S10 1TB specifically. I was considering buying one. I just thought that was interesting.

Cannot comment on specific video. I have watched other videos where it is clear that the iPhone reloads more. And it is my experience as well. Apple whole philosophy is we will do make things for you. Sure but it does not work for me. My apps get reloaded every 5 minutes. It is annoying as hell. It is why I never consider those iOS devices as serious productive machines. Reloading tabs and apps for me is a big NO NO.

 

[EugW]

Apple has always been stingy with RAM. They tend to put the lowest amount they can get away with.

The 9.7 didn't *need* the RAM as much as the 12.9. The Pro 12.9 has 5.6 million pixels compared to the Pro 9.7 which only has 3.1 million pixels. I imagine a task like gaming on the 2015 Pro 12.9 would be pretty poor if Apple only put 3-4GB in it. All things considered, the Pro 9.7 still performs quite well despite its limited RAM.

2 GB in the 9.7” Pro was a travesty.

Yes it *needed* more than 2 GB RAM, unless you think a Pro is just about playing games. It should have shipped with a minimum of 3 GB RAM.

It’s no surprise that the following year Apple shipped the 10.5” with twice the RAM at 4 GB.

 

[pshufd]

It's interesting that the 2019 iMac (not the iMac Pro) can take 128 GB of RAM and it's user-serviceable. I would like 32 GB of my next laptop, upgradeable to 128 GB if I want. High-end Windows laptops give you this already so it will be interesting to see if the 2019 MacBook Pros offer this as well.

It's an area that I'd expect Apple to step up on their iPads if they want to advertise them as laptop replacements.

I have no problems at all with 3 GB of RAM on my iPad Mini 5. The Mini 5 does everything I need it to do with grace and flair. But it's mostly a media consumption device for me. I might want more if I used it for trading like I do with my laptops.

 

[rui no onna]

2 GB in the 9.7” Pro was a travesty.

Yes it *needed* more than 2 GB RAM, unless you think a Pro is just about playing games. It should have shipped with a minimum of 3 GB RAM.

It’s no surprise that the following year Apple shipped the 10.5” with twice the RAM at 4 GB.

To be honest, the Pros weren't particularly Pro at the time. The Pro 9.7 was primarily just a successor to the Air 2 with added support for Apple Pencil and ASK, and option for larger storage.

Would 4GB have been beneficial? Yes, absolutely. It's not like the Pro 9.7 performs poorly with 2GB, though. It's actually noticeably faster than the Air 2. 1GB RAM on the original iPad Air was a travesty. 2GB on the Pro 9.7 isn't anywhere near as bad as that.

Lol, given how stingy Apple is when it comes to RAM, 4GB RAM on the 10.5 was a pleasant surprise. I had half expected them keeping 2GB still. Granted, I do believe the extra RAM was necessary for Split View + Slide Over. It wouldn't look good if the absolute latest Pro model couldn't do that.

 

[mspman]

There is no relationship between RAM and available disk space. Zero. There is a maximum amount of system memory (RAM) that can be used by a 64-bit processor (theoretically 2^64 = 16 exabytes but this is a theoretical limit). I can build you a system with 2Gb of RAM and 100Tb of storage, no problem. The max disk space depends on the type of file system used more than anything.

And the limits we are talking about are so large, any consumer device wouldn't even be a drop in the bucket.

 

[tps3443]

There is no relationship between RAM and available disk space. Zero. There is a maximum amount of system memory (RAM) that can be used by a 64-bit processor (theoretically 2^64 = 16 exabytes but this is a theoretical limit). I can build you a system with 2Gb of RAM and 100Tb of storage, no problem. The max disk space depends on the type of file system used more than anything.

And the limits we are talking about are so large, any consumer device wouldn't even be a drop in the bucket.

Well some doofus started this rumor about the 1TB iPad requiring extra ram for the storage lol. Why did he? I have no idea!

The Samsung Galaxy S10+ 1TB has 50% more ram too! Oh my goodness, it is also all available to the OS for general usage.. Just like the iPad Pro 1TB 6GB of ram is.

Why doesn’t any one question the Samsung? Well that’s easy! Because Samsung labels it as “The Ultimate Performance Edition”

Apple should have done the same I guess. Instead they add in 50% more ram, and assume the consumer could put two and two together.