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On 12/30/2015 10:14 PM, lee wrote: |
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> Hi, |
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> |
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> soon I'll be replacing the system disks and will copy over the existing |
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> system to the new disks. I'm wondering how much merit there would be in |
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> being able to make snapshots to be able to revert back to a previous |
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> state when updating software or when installing packages to just try |
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> them out. |
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> |
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> To be able to make snapshots, I could use btrfs on the new disks. When |
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> using btrfs, I could use the hardware RAID-1 as I do now, or I could use |
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> the raid features of btrfs instead to create a RAID-1. |
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> |
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> |
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> Is it worthwhile to use btrfs? |
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Yes. |
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;-) |
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> Am I going to run into problems when trying to boot from the new disks |
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> when I use btrfs? |
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Yes. |
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;-) |
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well ... maybe. |
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prepare for some learning curve. but it is worth it! |
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> Am I better off using the hardware raid or software raid if I use btrfs? |
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I would be picky here and separate "software raid" from "btrfs raid": |
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software raid .. you think of mdadm-based software RAID as we know it in |
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the linux world? |
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btrfs offers RAID-like redundancy as well, no mdadm involved here. |
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The general recommendation now is to stay at level-1 for now. That fits |
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your 2-disk-situation. |
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> The installation/setup is simple: 2x3.5" are to be replaced by 2x2.5", |
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> each 15krpm, 72GB SAS disks, so no fancy partioning is involved. |
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> |
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> (I need the physical space to plug in more 3.5" disks for storage. Sure |
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> I have considered SSDs, but they would cost 20 times as much and provide |
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> no significant advantage in this case.) |
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> |
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> |
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> I could just replace one disk after the other and let the hardware raid |
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> do it all for me. A rebuilt takes only 10 minutes or so. Then I could |
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> convert the file system to btrfs, or leave it as is. That might even be |
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> the safest bet because I can't miss anything when copying. (What the |
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> heck do I have it for? :) ) |
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> |
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> |
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> Suggestions? |
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I would avoid converting and stuff. |
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Why not try a fresh install on the new disks with btrfs? |
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You can always step back and plug in the old disks. |
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You could even add your new disks *beside the existing system and set up |
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a new rootfs alongside (did that several times here). |
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- |
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There is nearly no partitioning needed with btrfs (one of the great |
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benefits). |
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I never had /boot on btrfs so far, maybe others can guide you with this. |
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My /boot is plain extX on maybe RAID1 (differs on |
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laptops/desktop/servers), I size it 500 MB to have space for multiple |
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kernels (especially on dualboot-systems). |
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Then some swap-partitions, and the rest for btrfs. |
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So you will have something like /dev/sd[ab]3 for btrfs then. |
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Create your btrfs-"pool" with: |
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# mkfs.btrfs -m raid1 -d raid1 /dev/sda3 /dev/sdb3 |
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Then check for your btrfs-fs with: |
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# btrfs fi show |
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Oh: I realize that I start writing a howto here ;-) |
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In short: |
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In my opinion it is worth learning to use btrfs. |
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checksums, snapshots, subvolumes, compression ... bla ... |
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It has some learning curve, especially with a distro like gentoo. |
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But it is manageable. |
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As mentioned here several times I am using btrfs on >6 of my systems for |
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years now. And I don't look back so far. |
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- |
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look up: |
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https://btrfs.wiki.kernel.org/index.php/Using_Btrfs_with_Multiple_Devices |
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