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Bug#946682: debian-installer: Discard transmission by LVM



On Fri, 2019-12-13 at 17:15 +0100, Frederic MASSOT wrote:
> Package: debian-installer
> Severity: wishlist
> Tags: d-i
> 
> Dear Maintainer,
> 
> Following a discussion on the list of Proxmox users, I understood
> that only LVM Thin transmits discard commands to SSD.

This seems to be incorrect.  LVM normally uses dm-table, which supports
discard if the underlying device(s) do.

> https://pve.proxmox.com/pipermail/pve-user/2019-December/171187.html
> 
> https://pve.proxmox.com/pve-docs/pve-admin-guide.html#qm_hard_disk_discard
> 
> When creating logical volumes with the Debian installer, they are not
> of the LVM Thin type.
> 
> Can you add to the Debian Installer the ability to create logical
> volume with thin provisioning?

"Thin provisioning" is a device-mapper layer that allows assigning more
logical storage space than the underlying physical storage.  Newly
written blocks are allocated from the physical storage pool and
discarded blocks are returned to the pool.

This can be appropriate for disk server / VM host applications where
storage can be over-committed to VMs and more physical storage will be
added to the pool depending on actual need.  It does not seem to be
appropriate for the OS installation and therefore should not be offered
in the installer.

Ben.

-- 
Ben Hutchings
Anthony's Law of Force: Don't force it, get a larger hammer.


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