From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from taslin.fdn.fr (taslin.fdn.fr [80.67.169.77]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CB512231A23 for ; Sun, 31 May 2026 19:56:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=80.67.169.77 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780257372; cv=none; b=BD4LXhijWfrOZ+XWh6DDd0u8NHSLm1K6GcYYzd9RJfffjevTiifL8/4fawRiwKmH1TKVUwipXP+ygRXptJ/hnnlyFuSadjlxierC/JeXaQVv0tscJZBqLD/mODTQABxQNU3FMhmpGnNBsK47KGMgb56REvfHX4d73BOE62ustww= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780257372; c=relaxed/simple; bh=S0MguQ8Kb8tkXzVUig/Bbcf6m5KLJOKWxJmQQs/lmb4=; h=Date:From:To:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=uE+TsZ0iljXChu5NEiwXC0vo3q2/5Nt98dWpGYU+nxXAp43x4boH/3XBvt5TqDD4pgd3k8wBa5G7Ltwr9FdNgxnwOuJfY+TMUbbK83YaQWMcBdMjVBUrTkd7Gf7c504FZ4VriuLkbBvlkQoNTHbC3Jhbfkc6GzjfuHDs6uLYwDc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=max.gautier.name; spf=pass smtp.mailfrom=max.gautier.name; dkim=pass (2048-bit key) header.d=max.gautier.name header.i=@max.gautier.name header.b=Jy9SqzAW; arc=none smtp.client-ip=80.67.169.77 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=max.gautier.name Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=max.gautier.name Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=max.gautier.name header.i=@max.gautier.name header.b="Jy9SqzAW" Received: from localhost (unknown [IPv6:2a0c:e303:0:cc00:ba0f:ae98:a175:1ae]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by taslin.fdn.fr (Postfix) with ESMTPSA id 53D2560246 for ; Sun, 31 May 2026 21:46:56 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=max.gautier.name; s=fdn; t=1780256816; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=ikMwGwrMwlc9U+7Y5TNbQM0x35NdJu//rewxzmT79LU=; b=Jy9SqzAWzre+vUeQPsV3tU94Xc1xVFdRMcUKVM2/O5akY8PKPlRsHaakpOSevu3OYyneh9 RoMEHYqJgn3kdR7BoPVp/OneLkWHydtaDhZMGU7fPPuS2VpBYDwgzMi4OLTAHBI842MVb8 gxMEVRi85MP5GYco7b9Dsb8uPrg9LH8QJQO6bnJk7EBxsrwBepFYl85XAEcECKwRmvAVk8 bpCRn4gAODwrYU5ehA5JsHG/89Sk9iME29lQvBYKlKXHZSkkw10/6FEm8hdFa9dEsL95ag o15IybUL60q/2dCoAtK6rBBQeJMcDHwlOc+7G4QjvUXqfo/74ZNIkQJrxf8Jbg== Date: Sun, 31 May 2026 21:46:45 +0200 From: Max Gautier To: util-linux@vger.kernel.org Subject: Question: GPT GUID for dm-integrity separate metadata partition Message-ID: Precedence: bulk X-Mailing-List: util-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Hello, Some context: When using dm-integrity in Linux (device mapper target to provides transparent data integrity protection), one has a the option to use a separate device to store the integrity protection, (which can supposedly help offset the performance penalty on dm-integry by using a nvme for HDDs). While setting up my system (new RAID array on top of dm-integrity on each RAID member), I asked myself what GPT type those separate integrity partition should have, to avoid being confused as something else by other tooling. (for example systemd auto-mount some partition type, so I suppose some other tooling could have similar behavior) I considered 'Linux filesystem' and 'Linux reserved', but the first is not accurate and I could not find info on the second, so I do not know if it's reserved for future use (would seem odd seems GUID are plentiful) or for setup where we just don't want tooling to touch it ? I don't think Linux RAID is accurate either, (that would be the partition on the data disks instead). What's the recommendation when creating a partition not fitting any of the existing documented GUID ? Thanks. (In case this makes matter clearer, here is my intended setup): # lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS # Those are the raid disk with the data sda 8:0 0 14.6T 0 disk └─sda1 8:1 0 14.6T 0 part sdb 8:16 0 14.6T 0 disk └─sdb1 8:17 0 14.6T 0 part sdc 8:32 0 14.6T 0 disk └─sdc1 8:33 0 14.6T 0 part nvme0n1 259:0 0 1.8T 0 disk ├─nvme0n1p1 259:1 0 4G 0 part ├─nvme0n1p2 259:2 0 150G 0 part │ └─root 253:0 0 150G 0 crypt / │ # Those are the separate integrity partition (not sure exactly how │ much space I need for now) ├─nvme0n1p3 259:3 0 ???G 0 part ├─nvme0n1p4 259:4 0 ???G 0 part └─nvme0n1p5 259:5 0 ???G 0 part -- Max Gautier