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From: Zdenek Kabelac <zdenek.kabelac@gmail.com>
To: LVM general discussion and development <linux-lvm@redhat.com>,
	Gionatan Danti <g.danti@assyoma.it>
Cc: Demi Marie Obenour <demi@invisiblethingslab.com>
Subject: Re: [linux-lvm] Running thin_trim before activating a thin pool
Date: Mon, 31 Jan 2022 14:41:06 +0100	[thread overview]
Message-ID: <d768d362-4081-b91b-462c-e70fe40e32ba@gmail.com> (raw)
In-Reply-To: <9c35198501aae82e7a911f5418cfd7f6@assyoma.it>

Dne 31. 01. 22 v 12:02 Gionatan Danti napsal(a):
> Il 2022-01-29 18:45 Demi Marie Obenour ha scritto:
>> Is it possible to configure LVM2 so that it runs thin_trim before it
>> activates a thin pool?  Qubes OS currently runs blkdiscard on every thin
>> volume before deleting it, which is slow and unreliable.  Would running
>> thin_trim during system startup provide a better alternative?
> 
> I think that, if anything, it would be worse: a long discard during boot can 
> be problematic, even leading to timeout on starting other services.
> After all, blkdiscard should be faster then something done at higher level.
> 
> That said, I seem to remember that deleting a fat volume should automatically 
> trim/discard it if issue_discard=1. Is this not true for thin volumes?


'issue_discard' relates only to the internal lvm2 logic when some extents 
become free for reuse (so i.e. after 'lvremove/lvreduce/vgremove...'.

However since with thin volumes no physical extents of VG are released (as the 
thin volume is releasing chunks from the thin-pool) - there is no discard 
issued by lvm.

Regards

Zdenek



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  reply	other threads:[~2022-01-31 13:41 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-29 17:45 Demi Marie Obenour
2022-01-31 11:02 ` Gionatan Danti
2022-01-31 13:41   ` Zdenek Kabelac [this message]
2022-01-31 14:12     ` Gionatan Danti
2022-01-31 15:28   ` Demi Marie Obenour
2022-01-31 17:54     ` Gionatan Danti
2022-01-31 19:04       ` Demi Marie Obenour
2022-01-29 18:52 Demi Marie Obenour
2022-01-29 19:42 ` Zdenek Kabelac
2022-01-29 20:09   ` Demi Marie Obenour
2022-01-29 21:40     ` Zdenek Kabelac
2022-01-30  1:20       ` Demi Marie Obenour
2022-01-30 11:18         ` Zdenek Kabelac
2022-01-30 17:30           ` Demi Marie Obenour
2022-01-30 17:56             ` Zdenek Kabelac
2022-01-30 18:01               ` Demi Marie Obenour
2022-01-30 18:42                 ` Zdenek Kabelac
2022-01-30 20:22           ` Gionatan Danti

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