Not GP, but: I had replaced the battery on my M1 Max 6mo ago with an aftermarket part. On MacOS 26 that routinely gave about 5 hours of coding/browsing/active screen time (no audio or massive CPU load other than unit test runs).
Anecdotally, after updating to MacOS 27 2mo ago that time has been reduced by between a third and a half, doing the same kind of daily work on the exact same project, without major new apps installed or new always-open browser tabs.
I don’t know if it’s the OS’s fault directly or the fault of an app I use that interacts poorly with the new OS’s power management, but either one is damning. I’m not doing anything particularly weird.
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.
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.
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.
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.
It doesn't really do everything that a real LVM does though. This was used to support those annoyingly bad Fusion Drives. They dropped them around 2020 I think.
Erm... it was dropped in macOS 26 back in 2025 ?
https://www.techspot.com/news/108394-usb-killer-dead-apple-d...
Anecdotally, after updating to MacOS 27 2mo ago that time has been reduced by between a third and a half, doing the same kind of daily work on the exact same project, without major new apps installed or new always-open browser tabs.
I don’t know if it’s the OS’s fault directly or the fault of an app I use that interacts poorly with the new OS’s power management, but either one is damning. I’m not doing anything particularly weird.
Because it isn't LVM, and giving it the same name as another similar-but-distinct technology would just make matters more confusing.
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.
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.
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.
It manages logical volumes. Any quibbling is a matter of degree.