I’d say your best course of action is to : Use Carbon Copy Cloner to make a bootable clone to another drive just in case anything goes wrong Use Time Machine to back up as well Open Disk Utility > Select the physical internal drive in the left column (above ‘Macintosh HD’) Click partition > click the + button > adjust the partition sizes to suit > select APFS from the format for the new partition. It should warn that the original partition will be resized but not deleted. This may take a while if it has to shift data around. If this fails, reboot holding alt and select to boot from your external drive CCC clone, then retry. Disk Utility should be able to make any necessary repairs to the internal drive if you’re not booted from it. Download & install Catalina from the App Store > install to the new APFS partition Once Catalina’s sorted, reboot holding alt and select the El Capitan partition Open System Preferences > Network > Select ethernet/wifi/your active internet connection > from the cog-wheel menu set the network interface as inactive.
The Catalina upgrade will include a firmware upgrade for the iMac to allow it to boot from APFS formatted volumes and update Internet Recovery to always use the latest version of macOS in future, even 10.16 when it’s out, or will they go to macOS 11? who knows. I’ve just formatted an SSD here with HFS+, then split 50% partition with an APFS volume and it all seems to have gone through ok. A disk image won’t be bootable, hence the CCC backup first-thing to an external drive. _ Regards Sam Mullen +44 (0)7747778022 <tel://+447747778022> [email protected] <mailto:[email protected]> www.macambulance.com <http://www.macambulance.com/> MacAmbulance Ltd. Providing Affordable Mac/PC Support and Web Development MacAmbulance Ltd. is a registered company in England & Wales, registration number 8466597 This email is intended solely for the addressed recipients and may contain privileged or confidential information. If you have received this email in error please notify the sender and delete the email immediately. > On 6 Jul 2020, at 10:40, Route 49 Studio Brighton <[email protected]> > wrote: > > Hi all. I'm running a late 2012 imac 16gb Ram 1TB SSD. I've done quite a bit > of reading around this online and think I have a plan to achieve what I need > to but was hoping to run it past some people as I'm a bit paranoid about > making big changes on my system as I have a few jobs on the go and it would > be a big pain if I had to spend ages setting everything up again if I messed > it up! > > I run a small recording studio and have been using Logic 9 up until now > because I'm used to it and I haven't needed to change, but I do need to bite > the bullet and update now. > > I'd like to partition my drive so I can keep running my current Logic 9 > system on El Capitan on one partition that doesn't connect to the web and on > the other partition update to the latest OS and use Logic X and everything > else. > > I've got about 500gb on my drive at present. My plan is to: > > Backup all my important files on an hdd, they're already synced on Google > Drive set to never remove both copies. > > Create a disk image in disk utility as extra insurance. > > Then partition the drive. > > On the empty side I would then update to the new OS. > > Will this work? > > If I create a disk image is that bootable from? I'm keen to avoid having to > reinstall a legacy OS as I've heard this is a bit of a faff and I'd like to > keep my old setup runniong on El Capitan as I have ongoing projects and am > worried about plugin conflicts etc. if I try and run Logic 9 on the latest OS. > > Also when I partition the drive will it automatically place all the data on > one side? Presumably they will both be my current OS meaning I can then > update one partition while the other stays the same? > > Sorry for the long post. Many thanks in advance for any help. > > Ben > > -- > You received this message because you are subscribed to the Google Groups > "Sussex Mac User Group" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <mailto:[email protected]>. > To view this discussion on the web, visit > https://groups.google.com/d/msgid/smug/e5fad290-4620-4831-a26d-dce1d685442do%40googlegroups.com > > <https://groups.google.com/d/msgid/smug/e5fad290-4620-4831-a26d-dce1d685442do%40googlegroups.com?utm_medium=email&utm_source=footer>. -- You received this message because you are subscribed to the Google Groups "Sussex Mac User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/smug/97C1E75A-FEED-4169-9B33-BB78E548BF51%40macambulance.com.
