On Fri, 3 Apr 2015 17:05:43 +0300 Reco <recovery...@gmail.com> wrote: > Hi. > > On Fri, Apr 03, 2015 at 03:40:58PM +0200, Petter Adsen wrote: > > This ties in nicely with something I'm sitting here and wondering > > about right now. I'm preparing to upgrade my home server to Jessie > > today, and at the same time I want to set up something like LVM on > > the system disk (2x250G in mdadm RAID1). The main reason is that I > > want snapshots, and a secondary, nice-to-have-but-not-essential > > reason is future resizing of volumes. > > Both are possible with LVM. Snapshots require preliminary space > reservation for keeping the difference between a main filesystem and a > snapshot, and I/O may suffer somewhat, but that's it.
OK, good. Performance is no big deal in this case, the machine is just used as a file server. I intended to set aside a good chunk of space for possible future expansion of filesystems anyways, so there should be plenty available for snapshots. > Resizing just works, as long as you don't forget the correct order for > changing the filesystem and the volume. I.e. > > 1) Enlarge - volume first, filesystem last. > 2) Reduce - filesystem first, volume last. I expect the combination of ext4 and LVM is so common that ext4 would be a good choice of filesystem if I ever get the need to resize? > > The alternative to LVM would be btrfs, which would give me RAID1 and > > snapshots, plus subvolumes. I am familiar with mdadm, but I am *not* > > familiar with LVM or btrfs in any way. > > I'd stay clear of brtfs if I were you until jessie+1 (I forget > whatever its called) enters freeze. Then you install backported > kernel and *maybe* btrfs would be so kind and would not eat your data. That was what I was afraid of. <snip> > > What would the experts here recommend? I've been searching for a > > while now, but I haven't found anything recent that applies to both > > LVM and btrfs. I know btrfs is a moving target, is it stable enough > > to use for both it's RAID functionality and the rest? Or would I be > > better off with mdadm and LVM? Which is better to work with? > > You have mdadm. Add LVM on top of it. Make sure you have an non-LVM > EFI partition in case of using UEFI (does not apply to BIOS). Don't > forget to add busybox into initrd just in case. Enjoy. No EFI, just BIOS. Old machine. :) From what I understand, is it recommended to create a separate /boot that is not on LVM, or is that no longer the case? > If you really want to try btrfs - stay clear of both mdadm and LVM. > btrfs has own filesystem-aware LVM, and stacking LVMs never was a good > idea. No, I have no big desire to test it, I was just wondering if it would be a less complex solution to have both RAID and LVM-like functionality from btrfs than running both mdadm and LVM will introduce. But I think I will stick with mdadm + LVM. Thanks for your advice! Petter -- "I'm ionized" "Are you sure?" "I'm positive."
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