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pride moth stella⭐ @stellavie@tech.lgbt
4mo
Anything going against picking RAID-Z as a software RAID on 2-4 equally large HDDs? also wanna add an SSD cache (or maybe i should give the SSD directly to applications that generate previews and thumbnails)

or use LVM or btrfs with RAID-5? little bit confused which option to pick, but i think i want something with striping and parity
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Lyn@GPN24 📞 ACOW @fugi@amazonawaws.com
4mo
@stellavie Specifically btrfs RAID 5 (i.e. on fs level, not btrfs on raid 5) is a big no no. Last I heard there were still data loss problems.

Have you considered software RAID via mdadm btw? Not saying it's better than fs level RAID – actually considering using that instead in the future – but it's a well established option.
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pride moth stella⭐ @stellavie@tech.lgbt
4mo
@fugi oh well then im gonna keep my distance from it.

haven't looked into mapper raids so far, but going the beaten path is a good idea..

So far i'm most convinced by ZFS Raid (Raid-Z[1|2|...]) and i gotta compare it to that ^^'

with all the different methods there also remains the question for me what happens when the host OS stops working, will the raid be recoverable?
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Lyn@GPN24 📞 ACOW @fugi@amazonawaws.com
4mo
@stellavie It should be, would be pretty terrible if it wasn't 😅
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pride moth stella⭐ @stellavie@tech.lgbt
4mo
@fugi so basically the sensible options are

- LVM Raid + any FS
- mdadm Raid + any FS

- ZFS Raid with ZFS

and the ZFS Raid has some cool features which the others don't have?

www.diskinternals.com/raid-recovery/zfs-vs-mdadm-raid/

the only problematic thing i have found is that zfs is not in the kernel
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Lyn@GPN24 📞 ACOW @fugi@amazonawaws.com
4mo
@stellavie yeah, zfs brings its own hassles.

Regular btrfs raid (just not raid 5) should be fine too, just doesnt have native encryption last I checked
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Der Große Böse Wolff @wolff@chaos.social
4mo
@stellavie @fugi
how about the following stack
mdadm
dmcrypt/LUKS
LVM
XFS

Should be enough layers :)
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Der Große Böse Wolff @wolff@chaos.social
4mo
@stellavie @fugi Hot tip for mdadm: at setup use /dev/disk/by-id/ and save the invoked command into a git or something so you'll never be able to forget the specific order of your disks. It's the most important thing. Maybe also backup the superblock of every disk labeled with its unique by-id path.
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pride moth stella⭐ @stellavie@tech.lgbt
4mo
@wolff @fugi hmm, but why LVM and XFS and not btrfs >.<

so many choicessss
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Der Große Böse Wolff @wolff@chaos.social
4mo
@stellavie @fugi because btrfs does not have a good track record or is not matured enough yet in my eyes. Disadvantage of XFS: you can only grow it, no shrinking. Advantage: you can grow it while it is online and mounted

And at least until now XFS handled every sudden power loss I caused or witnessed without issues at all.

I would choose the one with more documentation that's easily available and searchable.
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Der Große Böse Wolff @wolff@chaos.social
4mo
@stellavie @fugi Regarding ZFS, I remember that is wasn't possible to add a disk to a zpool afterwards, at least a few years ago. That rendered ZFS very useless for a storage host with spare slots.
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Der Große Böse Wolff @wolff@chaos.social
4mo
@stellavie @fugi I think about switching my laptop over to ZFS since there is only a single nvme and I kinda want FS compression. I forgot what the encryption stack of ZFS looked like but LUKS2 does sensible modern crypto stuff by default, afaik.
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pride moth stella⭐ @stellavie@tech.lgbt
4mo
@wolff @fugi ah i see, well i think I might give this a try then!

not that it matters too much, but btrfs for the host os disk is fine, right? planning to use a USB and compression, since SATA connections are scarce in my setup
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Der Große Böse Wolff @wolff@chaos.social
4mo
@stellavie @fugi USB would be too prone to accidental unplug for me to consider running btrfs 24/7 over it. I don't trust the USB Connector and btrfs' failure handling. However I cannot provide a definitive source or explanation on this opinion and it may be wrong.
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Der Große Böse Wolff @wolff@chaos.social
4mo
@stellavie @fugi However if the operating system files are mostly immutable and the bulk of read write operations happen on another disk that's connected by SATA, then I guess I could be convinced to use btrfs on the system disk over USB (with backups ofc).
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pride moth stella⭐ @stellavie@tech.lgbt
4mo
@wolff @fugi it has been doing well for the past year except for atrocious IOPS, hence compression :3
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pride moth stella⭐ @stellavie@tech.lgbt
4mo
@wolff @fugi ahh i see, for what purpose do you add LVM to the stack or does LVM replace GPT? ^^
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Der Große Böse Wolff @wolff@chaos.social
4mo
@stellavie @fugi LVM gives me the option to randomly grow (or shrink) any logical volume at any time. A GPT partition table forces you to know what you need to split and how you split it (your filesystem tree) before you even have any data on it. Meanwhile LVM is able to pick a block (start and end position) of any size from the available space of your underlying physical volume and assign this block to a logical volume of your choice.
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Der Große Böse Wolff @wolff@chaos.social
4mo
@stellavie @fugi Try LVM out on a USB drive, create multiple LVs and grow them afterwards. Then have a look at /etc/lvm/lvm.conf (or something like that) and you'll see the mapping of blocks for each LV. Use the Archwiki for looking up LVM commands.
Put an XFS on a LV and try out this command (also documented in the arch wiki):

lvresize -L +2G --resizefs VGName LVName

Edit: no guarantees on the correctness on the above command. I typed this out of my memory.
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pride moth stella⭐ @stellavie@tech.lgbt
4mo
@wolff @fugi on a hardware raid, one would just drop mdadm from the stack, right?

Anddd... Bare Metal (Debian, Alpine?) or VM in Hypervisor (ProxMox VE)? :3

TrueNAS would make most sense with a ZFS setup, i suppose...
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Lyn@GPN24 📞 ACOW @fugi@amazonawaws.com
4mo
@stellavie @wolff hardware raid would be transparent to the operating system. You only need mdadm or similar to replicate that in software (both of which have their upsides and downsides).

Can't really comment on the rest, but I would not use a systemd-less distro for any deployment that does more than a single thing (e.g. a container or micro-vm).
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pride moth stella⭐ @stellavie@tech.lgbt
4mo
@fugi @wolff hmhm systemd is nice yes, currently using a distro without it but its mostly hosting docker containers anyways
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