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Can I format HDs and SSDs with APFS running El Capitan?
Posted: Thu Sep 27, 2018 12:02 pm
by FMiguelez
I've been doing some reading about APFS, and it seems like a very good and better file system than we've had up to now.
I wonder if I can use that format in my HDs and SSDs with my Macs running El Capitan?
One of them (the office one) won't allow me to instal anything higher than El Capitan... It's old, but still good enough for office duties. The other ones
can run Mojave, but at this point I'm only interested in APFS, not the rest of the OS.
The only thing that disappoints me about APFS is that, despite its new features, it seems it does
not do much for data integrity, i.e., bit rot
That's not particularly good... and I didn't get the feeling Apple will address that anytime soon. Hopefully I'm wrong about that!
Re: Can I format HDs and SSDs with APFS running El Capita
Posted: Thu Sep 27, 2018 12:59 pm
by bayswater
FMiguelez wrote:it seems it does
not do much for data integrity, i.e., bit rot
That only happens in hot climates
There was a workaround from Paragon that let you use APFS in earlier OS versions, but it was discontinued in August. If you google apfs in El cap you'll see a few others, but they all looked dodgy to me.
Re: Can I format HDs and SSDs with APFS running El Capita
Posted: Thu Sep 27, 2018 1:34 pm
by mikehalloran
The only thing that disappoints me about APFS is that, despite its new features, it seems it does not do much for data integrity,
How so?
APFS means strong encryption: The other big advantage to APFS is that it’s designed with encryption in mind. It combines the full disk encryption features found in the latest versions of OS X with the data protection feature that encrypts every file individually on iOS.
This fits Apple’s focus on privacy and security perfectly. When APFS is made available, you’ll have three options to choose from on macOS: no encryption, single-key encryption and multi-key encryption with per-file keys for file data and a separate key for sensitive metadata.
Re: Can I format HDs and SSDs with APFS running El Capita
Posted: Thu Sep 27, 2018 1:54 pm
by bayswater
mikehalloran wrote:The only thing that disappoints me about APFS is that, despite its new features, it seems it does not do much for data integrity,
How so?
APFS means strong encryption: The other big advantage to APFS is that it’s designed with encryption in mind. It combines the full disk encryption features found in the latest versions of OS X with the data protection feature that encrypts every file individually on iOS.
This fits Apple’s focus on privacy and security perfectly. When APFS is made available, you’ll have three options to choose from on macOS: no encryption, single-key encryption and multi-key encryption with per-file keys for file data and a separate key for sensitive metadata.
I think the reference is to whether your data lasts, not whether it can be hacked.
Re: Can I format HDs and SSDs with APFS running El Capita
Posted: Thu Sep 27, 2018 2:51 pm
by FMiguelez
Exactly!
I saw numerous references for security/privacy, which seems excellent, but nothing compelling about
data integrity.
Bit rot is just one issue, but I understand that, since the data in the SSD is constantly being rewritten and shuffled around, there should be redundant mechanisms to check the data constantly.
From what I've read, and I'm happy to be corrected, is that APFS doesn't do much checksums to prevent this. Not that it's bad, but could be much better...
https://arstechnica.com/gadgets/2016/06 ... -system/3/
Also, it may be I'm not understanding the full picture correctly

Re: Can I format HDs and SSDs with APFS running El Capita
Posted: Thu Sep 27, 2018 3:12 pm
by FMiguelez
bayswater wrote:
There was a workaround from Paragon that let you use APFS in earlier OS versions, but it was discontinued in August. If you google apfs in El cap you'll see a few others, but they all looked dodgy to me.
Ha!
You're right! I just checked and I didn't find anything that filled me with confidence about hacks for my precious files! No way!
Re: Can I format HDs and SSDs with APFS running El Capita
Posted: Thu Sep 27, 2018 4:54 pm
by bayswater
FMiguelez wrote:Exactly!
I saw numerous references for security/privacy, which seems excellent, but nothing compelling about
data integrity.
Bit rot is just one issue, but I understand that, since the data in the SSD is constantly being rewritten and shuffled around, there should be redundant mechanisms to check the data constantly.
From what I've read, and I'm happy to be corrected, is that APFS doesn't do much checksums to prevent this. Not that it's bad, but could be much better...
https://arstechnica.com/gadgets/2016/06 ... -system/3/
Also, it may be I'm not understanding the full picture correctly

On checksums, the article you cited says:
" Both NAND flash SSDs and magnetic media HDDs use redundant data to detect and correct errors. The Apple engineers contend that Apple devices basically don't return bogus data. NAND uses extra data, e.g. 128 bytes per 4KB page, so that errors can be corrected and detected. " There are checksums for the metadata, so at lease the way the OS sees your data is monitored by that. Somewhere else, they suggest that modern devices are good enough that they can be expected to return zero errors over their useful life. If so, could we be at the point where the checksum process is more likely to return an error than bad data?
The bit about the way copies are handled emphasizes the need to do backups.
Re: Can I format HDs and SSDs with APFS running El Capita
Posted: Fri Sep 28, 2018 10:26 pm
by mikehalloran
If that article was based on the Apple white paper (that doesn’t exist) and wasn’t written a year before the release of High Sierra, I’d give it some credibility instead of dismissing it as armchair speculation.
The bit about the way copies are handled emphasizes the need to do backups.
Since we don’t really know what’s going on—and neither does the author, that’s the safest attitude to have.