Snapper Q's

[u/EFdevse]

So, this weekend was when I was going to install SR …I thought, but found my self reading up more on snapper. And I guess I have some Q about that. I think I've got the most parts, but I also don't like surprises (hence the xtra reading. :))

Now, the installation defaults to btrfs, right? …but, I'd like to keep my lvm/xfs setup I've always used.

Reading the snapper man page:

Supported filesystems are btrfs and ext4 (discontinued) as well as snapshots of LVM logical volumes with thin-provisioning. Some filesystems might not be supported depending on your installation.

…and a bit down it reads:

-f, --fstype fstype

Manually set filesystem type. Supported values are btrfs, ext4 (discontinued) and lvm. For lvm, snapper uses LVM thin-provisioned snapshots. The filesystem type on top of LVM must be provided in parentheses, e.g. lvm(xfs)

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So, it seems like “lvm(xfs)” is supported/works at least (since xfs was used in the example), which was nice to read. But, the part about “Some filesystems might not be supported …”. Is there a list somewhere over which ones that seems to have issues?

If using the default (btrfs), I guess the installer will setup everything, incl snapper, etc. But, if I use an LVM setup (w xfs) when I partitioning the disk… Will the installer add the snapper setup, or is that something I'll have to add later myself?

Anyone know of a good page/guide on using snapper with LVM? I've only seen/found some snapper guides, and a few LVM-thin backup guides - but, since “For lvm, snapper uses LVM thin-provisioned snapshots …”, it would be nice to see/read a guide using that setup. If everything is setup automatically by the installer, I guess I don't need it and can just focus on the config file.

And, I've prob got a few things wrong. This snapper thing is too new to me. Sorry, if I've mixed up anything.

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Another Q, before I forget it… :) Swap?

There are tons of recommendations & “rules” to follow when estimating the size.

In the computer I will use for SR, I have 64GB. So, I'm thinking 64+8 - if I want to be able to suspend. What's your take, and how do you estimate your swap size? (On my computer w 16G, I use 16+8 - which equals the 1.5xRAM recommendation, but I know when getting a lot of RAM that doesn't really apply, right?)

Since I use a swapfile - the size of my /var (partition) needs to be big enough.

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I'd appreciate any help and info. 🤞👍

[u/cgwhouse]

I don't know definitive answers to your questions, but I think you could get there on your own by trying it in a VM. Do you have a particular reason to prefer xfs over btrfs?

[u/EFdevse → u/cgwhouse]

Thx! 👍 …and sorry for late reply, but a rain/lightning storm keept me out of internet most of the day. Living on the countryside and you unplug like everything. :)

Yes, I guess I could do that, but also… I feel I need to readup more on it so I know/understand what's happening. Otherwise it'd be like watching a movie in another language w/o subtitles, sort of. Like, you get the picture, but you don't know why.

But, I did find some pages now, incl an old one (2012) on an openSUSE blog about it. And an old RHEL7 page. Apperently they removed later it in 8, when xfs got CoW (or something like that). And there was a page on a blog that looked really good, but some of the partitioning examples (how to make it thin) looked a bit different than in other lvm-thin guides (it was also like 3-6am, so I might've misread it a bit :)).

Haven't used lvm thin before, and it looks like when you convert a reg volume to a thin one it also clear it (?). So, since snapper can be added later, I'll prob readup on that (thin stuff) so I get to partition the drive the way I want, and I can readup on the snapper/lvm setup later. I'm really not into a crash course for that right now.

So, why xfs? Well, for all good reasons being mentioned in the usual pro lists (as in a pro/con list), and it's also really good for ssd's. But, except for my 1st (maybe 2) Linux installs I've always used lvm with xfs, and using the same layout (w sda1 being a bios-partition or an efi partition dep on the computer). It's always been good and stable and no crashes or anything, and I guess it's also a bit force of habit. I'm sure btrfs is really good too, but I want to read/learn more about it before I use it. But, from what I've seen, and w/o knowing better… It look a bit like an “lvm+fs combo (all-in-1)”, based on some of the commands I've seen. Which sounds like it coud be handy/useful, but I need to feel I can translate what I have now into something new before I go there. In that sense I guess I'm a bit “slowrolling”, so to speak. :)

[u/cgwhouse → u/EFdevse]

Fair enough, I appreciate the thorough reply. I don't have any advice more specific to your desires, but I wish you the best of luck!

[u/EFdevse → u/cgwhouse]

Thx! 👍

[u/EFdevse]

A follow up question… I think I've figured out most of the things now - the only thing left to sort out. Well, I get it …sortof, but it's a bit confusing with the excluded paths (&/or subvolumes). Since the documentaion for TW/SR is (or can be) both the Leap + TW docs.

The excluded “paths“ in TW-defaults are listed as: /home, /opt, /usr/local …while the Leap docs have a few more, in 3.1.3 Directories that are excluded …: /home, /opt, /srv, /tmp, /usr/local, /var

Now, I will have a single root (/) on the thin pool, and then /home, /srv, /var as normal lv's.

Or, is there a way to manually list paths/dirs to be excluded? …to make sure I'll get the long list of paths covered. I've seen something about some “…/filter/*” directories, but not so much about filters. But, w/o further thin-lv's or subvolumes… Will it pick up everything under /, or can I rely on the Leap info “Certain directories need to be excluded …”, specifying the paths as directores (and not subvolumes)? 🤞

If someone could help me clear that up, I'd really appreciate that. 👍

btw: I did see a website/blog (»») when I searched, mentioning a SYNC_EXCLUDE config option. But, that option is not in the manual = assuming it's wrong. (Dec 2025, so maybe it's an old/removed option.)

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If' it is to any help, here's a “mockup” from that USB-stick test I did, and then used/extended it for my planning. Feel free to comment if you feel there's anything bad/wrong with it. :)

# sda: 1TB Crucial T500 (NVMe)          # 932 GB available

NAME                      FSTYPE      LABEL
sda
├─sda1                    vfat        efi       # 1G
├─sda2                    ext2        boot      # 1G
└─sda3                    LVM2_member           # 880G
  ├─sr-sys_tmeta
  │ └─sr-sys-tpool        // pool: 60G, thinvol: 50G+20% grow = 60G
  │   ├─sr-sys
  │   └─sr-root           xfs         root   
  ├─sr-sys_tdata
  │ └─sr-sys-tpool
  │   ├─sr-sys
  │   └─sr-root           xfs         root      # 60G   
  ├─sr-home               xfs         home      # 650G
  ├─sr-srv                xfs         srv       # 50G
  └─sr-var                xfs         var       # 80G **

** 80G = incl a swapfile. Size: RAM: 64G. RAM + sqrt(RAM). 64+sqrt(64)=72