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HDD vs. SSD
#46245 09/09/17 12:13 AM
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Jon

macOS 10.15.6, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365
Re: HDD vs. SSD
jchuzi #46249 09/09/17 01:06 PM
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Interesting, but in dispelling the 4th myth (SSD capacities are less than HDD's) they support some of myth #1 (SSD prices are incredibly high): the cost of a comparable SSD setup is about 8 times the cost of one with hard drives. smirk


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Re: HDD vs. SSD
Ira L #46250 09/09/17 01:34 PM
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If you can afford it, the advantages of SSDs outweigh HDDs. As always, you get what you pay for.


Jon

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Re: HDD vs. SSD
jchuzi #46251 09/09/17 02:37 PM
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I notice from your iMac details that it's using a Fusion drive.

Based upon your comments, I'm curious if you are considering changing to an iMac solely using an SSD internal drive?


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Re: HDD vs. SSD
pbGuy #46252 09/09/17 03:03 PM
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My iMac is doing fine and I'm sticking with it for the foreseeable future. It may be possible to swap the fusion drive for an SSD, but the procedure is way beyond my abilities.


Jon

macOS 10.15.6, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365
Re: HDD vs. SSD
jchuzi #46254 09/09/17 04:01 PM
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Originally Posted By: jchuzi
My iMac is doing fine and I'm sticking with it for the foreseeable future. It may be possible to swap the fusion drive for an SSD, but the procedure is way beyond my abilities.
Having once trashed a Mac mini when upgrading the HD I did not want to take a chance on the one I had. So on a Monday, I overnighted my Mac mini to OWC in a box they provided and for a very nominal installation fee plus the cost of the hardware OWC upgraded the SSD portion of the Fusion Drive to 1TB and had the Mac mini back to me by Friday.

OWC restored the data on on the Fusion drive and configured it as a single Fusion drive. It took one cut and pasted terminal command to separate the two portions of the Fusion drive into separate drives. Although I had been satisfied with the speed of the Fusion Drive, going to an all SSD boot drive blew me away.


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Re: HDD vs. SSD
joemikeb #46255 09/09/17 07:54 PM
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The ATO options for SSD in a new Mac are quite the premium. Do the new iMacs fit the regular shape of 3rd party SSDs (e.g. the ‘big’ 2TB ones)? Are the SSDs that Apple places different in any way? There used to be a lack of TRIM support for 3rd party SSDs, iirc. Is that still a thing, and how important is that?

Re: HDD vs. SSD
Urquhart #46256 09/09/17 09:25 PM
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The newest SSD only Macs use PCIe-based flash drives and are not compatible with third party drives that use a SATA interface. I just checked OWC and Crucial and neither offered upgrade or replacement SSDs compatible with SSD only Macs later than 2015 models. Both offer SSDs to replace SATA HDs in Macs so equipped. I don't know about the SSD portion of Fusion drives in more recent iMacs but if the SSD is SATA it could be upgraded to a larger SSD and certainly the HD portion could be replaced with a third party SSD.

The reason Apple has moved away from the SATA interface for SSDs is the SATA bus is significantly slower than the SSD and becomes a drive I/O choke point.


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Re: HDD vs. SSD
Urquhart #46257 09/09/17 09:28 PM
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And... How to Enable TRIM on Third Party SSDs in Mac OS X with trimforce

More: The command works with internal drives only, I believe. If TRIM can be enabled on external drives, someone else will have to kick in with how.

Apple-installed SSDs are awfully pricey, but their RAM and HDDS have always been pricey, too. frown

Last edited by artie505; 09/10/17 07:25 AM. Reason: More

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Re: HDD vs. SSD
artie505 #46681 10/24/17 04:04 AM
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There are a few non-free GUIs that do that with a custom driver (thus without modifying system files) even on older Macs and systems: Trim Enabler or Disk Sensei [same developers].

Originally Posted By: artie505
More: The command works with internal drives only, I believe. If TRIM can be enabled on external drives, someone else will have to kick in with how.

Lifewire notes: A Few Additional Notes About TRIM. TRIM isn't supported in external enclosures that use USB or FireWire as the method of connection to your Mac. Thunderbolt enclosures with SSDs do support the use of TRIM.


Another thing on SSDs that I was thinking about: Would TRIM work/be functional on an encrypted disk? I presumed that free space on a disk is also encrypted (and thus never be marked as available space on the low level that TRIM will zero), but it turns out File Vault (File Vault 2 whole disk encryption) doesn’t work that way. The free space is not part of the vault, and TRIM will empty those blocks just as with an unencrypted disk. Encryption purists wouldn’t be happy about that, as even the amount of free space could be a marker, that real full disk encryption wouldn’t give away.

Re: HDD vs. SSD
Urquhart #46682 10/24/17 07:33 AM
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Originally Posted By: Urquhart
Another thing on SSDs that I was thinking about: Would TRIM work/be functional on an encrypted disk? I presumed that free space on a disk is also encrypted (and thus never be marked as available space on the low level that TRIM will zero), but it turns out File Vault (File Vault 2 whole disk encryption) doesn’t work that way. The free space is not part of the vault, and TRIM will empty those blocks just as with an unencrypted disk. Encryption purists wouldn’t be happy about that, as even the amount of free space could be a marker, that real full disk encryption wouldn’t give away.

I'm pretty sure that joemike has posted that full disk encryption in APFS High Sierra encrypts even free space.


The new Great Equalizer is the SEND button.

In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire
Re: HDD vs. SSD
artie505 #46683 10/24/17 12:03 PM
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Originally Posted By: artie505
I'm pretty sure that joemike has posted that full disk encryption in APFS High Sierra encrypts even free space.

FYI in case anyone is wondering "why would you encrypt free space?", it is the ultimate goal of data encryption to prevent someone without the key from gaining any knowledge of the contents, or even lack thereof. IE you shouldn't be able to identify the one hard drive with all the data on it compared with the other nine in the bin that are freshly formatted. Someone trying to sneak a hard drive out of a secured area that encounters a stack of removed drives would positively love to be able to identify which of the ten they need to nip off with for analysis, rather than be forced to try to smuggle all ten of them out the door.

I ran into this exact issue several years ago while working at an AASP retailer. A vendor sent us a demo unit of a new "hardware encrypted drive". It was a USB external drive, but it also had a USB-A port on the back, and came with what looked like a flash drive. But it wasn't a flash drive, it contained the key to the external drive. If the key was not plugged in, the drive was encrypted. Pulling the key was like locking the drive.

Seemed like a nice idea, and my boss gave it to me to check out. I quickly discovered that the drive used a 32 bit block encoding scheme that had no salt for the block number. (it was not a stream cipher) This meant that every four bytes were encrypted together, the same way. So regions of the hard drive with no data on them were easily identified by a pattern of the same four bytes, repeated over and over.

The first thing that stuck me is I could immediately identify a drive that at one time contained information vs a drive that had been wiped, because empty blocks were so obvious. But it then occurred to me I could also start identifying structures on the drive such as partition scheme, number of partitions, etc, because of areas of blocks that were zeros or not zeros. ("this is a fat-32... that one is HFS+" and so on) And since some areas in the partition tables were known fixed values, I could see the encrypted patterns at those locations and knew what that pattern stood for, allowing me to identify it anywhere else it occurred on the drive. ("this is what a '1' looks like. this is the string 'AFPS'", etc)

Allowing me to get ANY of this information would be cause for concern. And in the business of crypto-analysis, every nugget of information your protection "leaks" is another crack in the armor that may eventually lead to a catastrophic failure. (go read up on Enigma, a great example of that IRL)

I took the time to try to contact the manufacturer, and engaged in a short discussion with them. I could quickly summarize our discussion with "They didn't consider it to be a problem."

Needless to say, we didn't stock any of these new drives.



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Re: HDD vs. SSD
artie505 #46684 10/24/17 02:52 PM
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Originally Posted By: artie505
I'm pretty sure that joemike has posted that full disk encryption in APFS High Sierra encrypts even free space.

You are correct that APFS (encrypted) and MacOS Extended (encrypted) formatted drives in Sierra and High Sierra are fully encrypted. That was not true in earlier versions of Filevault and I am not sure when full disk encryption was enabled but I do know it is the case in Sierra and High Sierra. The process of Filevaulting a drive is no small thing and can take days to complete (but you can still use the drive while that is in process).

Full data stream encryption of telecommunications has been used by the military for well over half a century. The surprise to me is it has taken this long to make its way into data storage security protocols. As Virtual1 so clearly pointed out, it only takes a tiny wedge to enable crypto analysts to get the data if they want it badly enough. With today's fast and relatively cheap computers even curiosity may be enough of an incentive to go after any data.


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Re: HDD vs. SSD
Virtual1 #46685 10/24/17 02:55 PM
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Thanks for shining that "real life" light on a highly technical and abstract subject.

Beyond that, though, isn't empty space encryption far more important as respects SSDs than it is as respects HDDs because of the fact that SSDs retain data even after they've been "erased"?

Originally Posted By: V1
Needless to say, we didn't stock any of these new drives.

Did anybody buy them?

Last edited by artie505; 10/24/17 03:02 PM. Reason: Add quote

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Re: HDD vs. SSD
artie505 #46686 10/24/17 06:28 PM
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Originally Posted By: artie505
Beyond that, though, isn't empty space encryption far more important as respects SSDs than it is as respects HDDs because of the fact that SSDs retain data even after they've been "erased"?

Who said magnetic HDs don't retain any data when they have been erased? It all depends on how badly someone wants the data. Even the 7x overwrite is NOT foolproof. There are labs that can go deeper than that. The only foolproof erasure is a grinder that reduces the platter to dust.


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Re: HDD vs. SSD
joemikeb #46694 10/26/17 11:00 AM
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Originally Posted By: joemikeb
Originally Posted By: artie505
Beyond that, though, isn't empty space encryption far more important as respects SSDs than it is as respects HDDs because of the fact that SSDs retain data even after they've been "erased"?

Who said magnetic HDs don't retain any data when they have been erased? It all depends on how badly someone wants the data. Even the 7x overwrite is NOT foolproof. There are labs that can go deeper than that. The only foolproof erasure is a grinder that reduces the platter to dust.

While a 7 pass overwrite of a HDD is, as you say, nowhere near a panacea, a 35 pass overwrite, which is readily available in appropriate versions of Disk Utility, is pretty close...closer, to the best of my knowledge, than directory erasure which leaves our data intact, our only option with SSDs.

As you recently said, "[As Virtual1 so clearly pointed out,] it only takes a tiny wedge to enable crypto analysts to get the data if they want it badly enough."


The new Great Equalizer is the SEND button.

In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire
Re: HDD vs. SSD
artie505 #46698 10/26/17 05:42 PM
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Originally Posted By: artie505
isn't empty space encryption far more important as respects SSDs than it is as respects HDDs because of the fact that SSDs retain data even after they've been "erased"?

Well the issue here is that the TRIM command won't change the contents of a block. What it WILL do is return all zeros. And for an encrypted-free-space device, that's a problem because now it can clearly be seen as empty. Ignoring the data that's actually still in the nand cells on the device, the analyst will immediately be able to see which blocks "should contain current information". I call that a bad thing. It's not straight-forward useful information to many, but ANY information I can get from an encrypted device counts against it. So if you want to properly erase an encrypted drive, you have to zero it, encrypted, and never use TRIM. I suspect we'll start seeing more SSDs that have built-in support for full-disk encryption though, which will then be able to use TRIM to "zero" a block without having to burn another write-cycle or take the time required to actually change all those blocks if you're formatting.

Quote:
Originally Posted By: V1
Needless to say, we didn't stock any of these new drives.

Did anybody buy them?

I have no idea. I don't do sales, and rarely needed to come up front and help out.


I work for the Department of Redundancy Department
Re: HDD vs. SSD
Virtual1 #46751 11/01/17 07:41 AM
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Originally Posted By: Virtual1
So if you want to properly erase an encrypted drive, you have to zero it, encrypted, and never use TRIM.

(Sorry, but I can't begin to locate the thread I'm about to cite.)

A while back, tacit posted SSD statistics that (if I remember correctly) showed that in many, if not most, instances their write capacities - even without TRIM implemented - far exceeds the useful lives of the machines they're in.

That, taken together with V1's quoted statement, suggests that most of us who are really concerned about the security of the contents of our Macs may be best served by implementing V1's advice, because in many instances TRIM does no more than lengthen the life of devices that are already longer, maybe even far longer, lived than they need to be.

Quote:
Originally Posted By: V1
Needless to say, we didn't stock any of these new drives.

Originally Posted By: artie
Did anybody buy them?

I have no idea. I don't do sales, and rarely needed to come up front and help out.

You already said that you didn't stock them. wink

I was asking whether the product, itself, flew or was dead in the water to others as it was to you?


The new Great Equalizer is the SEND button.

In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire
Re: HDD vs. SSD
artie505 #46753 11/01/17 04:00 PM
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Originally Posted By: artie505
Quote:
Originally Posted By: V1
Needless to say, we didn't stock any of these new drives.

Originally Posted By: artie
Did anybody buy them?

I have no idea. I don't do sales, and rarely needed to come up front and help out.

You already said that you didn't stock them. wink

I was asking whether the product, itself, flew or was dead in the water to others as it was to you?


Well I meant we didn't buy any more of them for restock beyond our initial purchase, if any. (that may have been a demo drive I was given to play with, in which case we sold zero of them)

I never saw it again there, nor anywhere else. I assume it was a flop in the market.


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