Help with reinstalling Sparky alongside eOS

[PNWDrew]

I'm going to reinstall sparky due to a bunch of issues I don't have the skill to solve.

Sparky was the first OS on the drive and I put eOS on after.
This is what gparted shows (from within the eOS install if it matters)



I have 3 related questions:

1 - Sparky should be in sda1 if I interpret that correctly.  How do I reinstall it without messing up my ability to boot into the new Sparky and eOS at will? Can I just format sda1 and let Sparky installer do it's thing?
2 - Can I shrink the sda1 partition without affecting the other OS? I see the option in GParted but also see warning in online help about changes affecting other partitions.

If you didn't guess I am a noob at this so don't assume I know anything!

Drew

edited  - removed ? about E19...

[jwhitmor]

Maybe you could give us a little more information about your system. I am an old codger, and to me, eOS should be on an antique CDC-ETA10 supercomputer. That eOS probably did not even have a boot loader as we know it. In general, you would install the eOS first, saving space for Sparky, and when you install Sparky it should be considerate of what is already on your disk. If you need something more specific, the installer has a manual disk partitioning option with a button to select advanced formating options. You need 30 GB for the system install "/" partition, and additional partitions for swap, and home, as you desire. Then hopefully Sparky will correctly set up the Grub boot loader for both O.S. If not, you will need to look up how to modify Grub, so that your Dual boot can work. I suppose another option would be leave eOS alone, and install a bootable image of Sparky on a USB stick, or external USB drive.

[PNWDrew]

Maybe you could give us a little more information about your system. I am an old codger, and to me, eOS should be on an antique CDC-ETA10 supercomputer. That eOS probably did not even have a boot loader as we know it. In general, you would install the eOS first, saving space for Sparky, and when you install Sparky it should be considerate of what is already on your disk. If you need something more specific, the installer has a manual disk partitioning option with a button to select advanced formating options. You need 30 GB for the system install "/" partition, and additional partitions for swap, and home, as you desire. Then hopefully Sparky will correctly set up the Grub boot loader for both O.S. If not, you will need to look up how to modify Grub, so that your Dual boot can work. I suppose another option would be leave eOS alone, and install a bootable image of Sparky on a USB stick, or external USB drive.

Sorry, I wasn't very clear in the post.. eOS = ElementaryOS, a Ubuntu based distro.  I didn't even know there was an older OS with that name. I've been on the ElementaryOS forums and became accustomed to abbreviating it.
ElementaryOS installed and recognized Sparky on disk.  It's installer did whatever it does and so Grub sees both and allows a choice.  I would expect a new Sparky install on the existing Sparky partition would just recognize the other OS and do it's thing.  But I have made assumptions like that before and regretted it before so I am being cautious this time.
It's a modern home-built PC.  AMD K10-7850K CPU on a Gigabyte mobo with a Samsung 120gb SSD.

Thanks
Drew

[jwhitmor]

OK, I like Elementary OS, and I liked another version called "Pear OS" even better (until somebody killed it).
  The Sparky Installer should get to the partitioning page, and ask you in a menu box, what partition you want to use as root, and what format you want to use for it (EXT4) and then also what partition you want to use for /swap (Linux swap format) and for /home (EXT4).  You highlight the correct partition by clicking on it, and re-use the same partition created from the first install. If you have a reason to change any partition (example, make it larger) then you can run GParted right from the installer.  Hopefully then, the installer will complete, and grub will flawlessly install the correct boot-loader entries. As usual, no guarantees. Your only insurance is a full backup of anything you do not want to lose. Sometimes you only learn some stuff by a failure, and then start over and try it again.

[PNWDrew]

Ok thanks for the help! I'm think I am going to create several partitions so I can safely play with several distros at once.  I may attempt to share a data partition between them because that seems handy to have.