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Comment by duskwuff | Hacker News Reader

> Why they didn't just refer to it as LVM is beyond me.

Because it isn't LVM, and giving it the same name as another similar-but-distinct technology would just make matters more confusing.

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According to the Wikipedia article about CoreStorage, it seems like the primary/only use case was Fusion drives (hybrid SSD/HDD hardware).

The article says “It renders your expensive storage hardware completely useless.” but I’m really curious what that hardware could actually be. This seems like a pretty dead technology.

Sidebar, but as an end user, I remain annoyed that there isn't seemingly something that's a worthy successor to fusion drives.

Like I have an Unraid box with dual NVMe (RAID1) as the "cache" drive and a bunch of spinning disks as the "array", but it's also very manual, like torrents get downloaded first to cache and then a nightly job syncs them to the array. Feels like a real missed opportunity to not be able to have this kind of config transparently managed.

bcachefs with foreground_target/background_target/promote_target set appropriately does this automagically: https://bcachefs.org/Caching/

Ah nice, I appreciate the search term, and I see there are some projects out there leveraging this, for example: https://github.com/nasty-project/nasty

Overall I'm happy enough with Unraid for the moment, but I will definitely check in on bcachefs-based solutions when I'm next considering a rebuild/upgrade.

The successor is SSDs, and I think for what Apple was using fusion drives for they are worthy successors.

The 2.5” form factor also took up a ton of space in a laptop form factor.

With my NAS box (TrueNAS ZFS) I don’t bother with a cache. I struggle to justify the cost/benefit ratio. The sustained write speed of a 3.5” disk isn’t so bad for the most common NAS use cases.

If I could go back to 2024 I think I’d use a m.2 2280 array for my NAS just because my present tense brain would think it was cheap. I don’t even hoard that much content so 4-8TB would be fine.

Maybe one of these nifty things would be fun: https://www.bee-link.com/products/beelink-me-mini-n150

From a pure cost point of view, I think it still makes sense to me to split the load, like 500GB of NVMe covers your containers and apps and stuff, but then 10-20TB of spinning storage is fairly achievable with redundancy, whereas that would cost a fortune to do as all solid state.

The case I have is a Jonsbo N2, which works great for accommodating 5 3.5" drives with backplane, a mini-ITX mobo: https://www.amazon.ca/N2-Aluminum-Support-Integrated-Removab...

Windows storage spaces can do this as well. It's been pulled from the non server line for 11 years or something.

I've gotta agree. I'm not sure what expensive storage hardware would be both relevant today and unable to migrate off CoreStorage. For example, my most expensive storage is a NAS with an iSCSI target, and it couldn't care less what blocks I write to it. If I had a CoreStorage setup on it, I could migrate the data to a new target and then reuse that space for something else. The hardware wouldn't mind, or even know, that I'd changed what's on it.

You mentioned old, obsolete Fusion drives. I'm having a hard time thinking of anything else where that'd matter, so you're probably right about that. AFAIK you can reformat those to use something other than CoreStorage if you're actually stuck using those boat anchors.

I have one of those in an ageing late 2009 27" iMac running Linux. It is a Seagate ST2000DX001-1CM1, a 2TB "SSHD" which comes down to having 8 GB of NAND storage bolted on to a conventional 2TB drive. It doesn't need any special driver to do its thing so I wonder what that CoreStorage bit is supposed to be about.

Apple sold iMacs for many years that had a completely separate SSD and HDD, and CoreStorage was used to combine them into a single block device which was then partitioned and formatted as HFS+ or APFS.

You could also do this to your own SSD and HDD, though probably only a good idea with internal ones like in a Mac Pro

Did you install that SSHD as an aftermarket upgrade? I thought the Fusion Drive configurations shipped by Apple used normal hard drives and separate SSDs and were purely software-managed (and also used much more than 8GB of flash).

CoreStorage was also used for HFS+ formatted and encrypted external storage like Time Machine backups. If you have any of those in your archive you might not be able to read them in the future.

Does it not manage logical volumes?

Yes it does. It's basically lvm for Mac. I wonder what they do now. Do they go back to old style fixed volumes?

...like route 53? which is "dns configuration, but fancier"

AFAIK "Route 53" was a net new name for such a product?

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