Anaconda's default partitioning scheme when installing to an SSD+HDD system (F21)
I've had the good fortune of getting a new workstation equipped with a 256GB SDD and a 1TB HDD. I've essentially split each drive in half to dual boot Windows 7 and Fedora 21. My intention is to use the SSD for the OS + frequently accessed files while using the HDD for bulk storage and any "write heavy" operations that might put unnecessary wear on the SSD. After installing Windows 7 to the two "half"-drives, I insalled Fedora using Anaconda's automatic "dual-boot" option to install along side a currently present OS.
Anaconda reacted by setting up LVM, with one volume group for all of the remaining free space on both drives. It then created three logical partitions within it: swap (17 GB), root (54 GB), and home (557 GB). The output of fdisk --list is shown below.
Disk /dev/sda: 238.5 GiB, 256060514304 bytes, 500118192 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xac7c8796
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 206847 204800 100M 7 HPFS/NTFS/exFAT
/dev/sda2 206848 250161151 249954304 119.2G 7 HPFS/NTFS/exFAT
/dev/sda3 250161152 251185151 1024000 500M 83 Linux
/dev/sda4 251185152 500117503 248932352 118.7G 5 Extended
/dev/sda5 251187200 500117503 248930304 118.7G 8e Linux LVM
Disk /dev/sdb: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0x55355c42
Device Boot Start End Sectors Size Id Type
/dev/sdb1 2048 976762879 976760832 465.8G 7 HPFS/NTFS/exFAT
/dev/sdb2 976762880 1953523711 976760832 465.8G 8e Linux LVM
Disk /dev/mapper/fedora_dh3203--t1700--1-swap: 15.7 GiB, 16844324864 bytes, 32899072 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/mapper/fedora_dh3203--t1700--1-root: 50 GiB, 53687091200 bytes, 104857600 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/mapper/fedora_dh3203--t1700--1-home: 518.7 GiB, 556949045248 bytes, 1087791104 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/sdc: 14.9 GiB, 16008609792 bytes, 31266816 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x929e2b69
Device Boot Start End Sectors Size Id Type
/dev/sdc1 2048 31266815 31264768 14.9G c W95 FAT32 (LBA)Is this setup efficient as far as utilizing the disks? In other words, is LVM aware of how to best split up data between the SSD/HDD physical drives for good ...
Welcome to ask.fedora, and thank you for asking such a well thought out question and giving us so much needed information. I'm not familiar with SSD usage, so I can't answer that part of your question. I can tell you, however, that in my personal opinion, LVM is not a good solution for a personal computer, although it probably comes in handy on servers. If you're going to reinstall, you're probably better off using a custom partitioning scheme so that you can, among other things, have a separate /home that's not on the SSD.
Thanks for your suggestion! Interesting that Anaconda would default to using LVM for the "workstation" edition in that case, but it perhaps would be convenient if you wanted to transparently treat multiple drives as one big one. In regards to your suggestion, I wonder if it is possible to consolidate my logical volume (spanning one partition on each drive) to a single partition on only the SSD. That is, without reinstalling from scratch. Of course, using LVM wouldn't be necessary in this case, anyway.
I doubt that very many people have that need on workstations or home computers. I don't know why LVM is the default for workstations, but that goes back to before there was a distinction at install time between workstation and server. My guess is that the devs all use it and don't realize that it's not really needed for most private uses.