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Reserve space for specific thin logical volumes

linux-lvm matthew patton 2 participants 2 messages Sep 11, 2017 – Sep 12, 2017 1 message not in the archive

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Let me de-tour by using ZFS as an example

with the obvious caveat that in ZFS the block layer and the file layers are VERY tightly coupled. LVM and the block layer see eye-to-eye but ext4 et. al. have absolutely (almost?) no clue what's going on beneath it and thus LVM is making (false) guarantees that the filesystem is relying upon to actually be true.

IMO Thin-Pool is like waving around a lit welding torch - it's incredibly useful to do certain tasks but you can easily burn yourself and the building down if you don't handle it properly.

#2 lore raw

Il 12-09-2017 00:56 matthew patton ha scritto:

Quoted 5 lines

with the obvious caveat that in ZFS the block layer and the file layers are VERY tightly coupled. LVM and the block layer see eye-to-eye but ext4 et. al. have absolutely (almost?) no clue what's going on beneath it and thus LVM is making (false) guarantees that the filesystem is relying upon to actually be true.

Sure, but in the previous examples, I did *not* use the ZFS filesystem part; rather, I used it as a logical volume manager to carve out block devices to be used by other, traditional filesystems.

The entire discussion stems from the idea to let thinp reserve some space to avoid a full pool, by denying new snapshot and volume creation when a free space threshold is crossed.

Thanks.

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