From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sfwd06.p.bluenet.ch (sfwd06.p.bluenet.ch [193.247.246.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0B619848C for ; Wed, 20 Nov 2024 01:44:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.247.246.19 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732067087; cv=none; b=teNI2SeQoIX3P6fQzmnWIF8D3ESoRsRVuF+K0Ah/rMKl8mMWHLr1p3TK73whjuzaaf+bOYhsMwSUlZDVSjnbirsQKTcn+LnBp6miCL9rYEFKkQeQDyqPSRdl0q4J7CN5fh6E4DJuWMGsGtLpJtRNUnHzPwayW8gR+4SdomI65JQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732067087; c=relaxed/simple; bh=dPow0NurtUZLwUqen1D27znT0lg9YsKQgWUMrTGZqT0=; h=Message-ID:Date:Subject:From:To:MIME-Version:Content-Type; b=YO87SvA8bEuIxHgHMx8++IiVE+TZg8UTy02KtcmwG4EutzpSUknxhSRVNJMdH9KIoIiicDf+FM46CSj3aRJEGde16osU72DR+quSugpPFlQ16aR5soMuRqQ2ph3DsoyKFHwBmW7nvTIb4k3K1Cjl+j1dIHCuMdX6HVe6Mp+ram4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=bluewin.ch; spf=pass smtp.mailfrom=bluewin.ch; dkim=pass (2048-bit key) header.d=bluewin.ch header.i=@bluewin.ch header.b=NtdVgSEm; arc=none smtp.client-ip=193.247.246.19 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=bluewin.ch Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bluewin.ch Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bluewin.ch header.i=@bluewin.ch header.b="NtdVgSEm" Received: from main ([84.227.21.131]) by vimdzmsp-sfwd06.bluewin.ch Swisscom AG with ESMTPA id DZlqto3f6WdHXDZlqtur5M; Wed, 20 Nov 2024 02:44:42 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bluewin.ch; s=fxzs-2048-20230414; t=1732067082; bh=JnTWB2RJYO299iaEG9S8vcDCuum8fys3QnL6mK3l8Es=; h=Message-ID:Date:Subject:From:To:MIME-Version; b=NtdVgSEmHz/zcHSN7d3mLr6Db2rnMRISpTwRRHrwXpO3U53U/5hTrMSymzVjNfhK7 ljZjyb00xibIMJZNo0ulBNFs/6XgBD9PT25jFxTAgDpJWeOZvy3sh5IOywEkEz6sbe uoMTBHFLwatroJBXP7FHMEXrwgMiVi4V0anrs0agf6rdfrqG5DR2M2sw0t3YchTxrQ TABlw5kPvf+rIrJXJnXkt1W0tGwWP8NZD8VdVUBhYrqYmAaRhkwgSClUZiJoJMEfOD cqXzSBF3QjnxcUkF++emPE0pypQTWjbpaGB25XV5vM/JHhXci3LwJx6+C9RKonPodp qiAWw0K6fphlg== X-Bluewin-Spam-Analysis: v=2.4 cv=M5juKDws c=1 sm=1 tr=0 ts=673d3f0a a=ig9bzvNBGao8Dw96AwO3EA==:117 a=ig9bzvNBGao8Dw96AwO3EA==:17 a=8nJEP1OIZ-IA:10 a=VlfZXiiP6vEA:10 a=LLPZWm0_0O8A:10 a=UnFn9vWkAAAA:8 a=-hsQUwj1i2190egUvwYA:9 a=wPNLvfGTeEIA:10 a=5uXxjHYwiSDyE7QCaOg_:22 X-Bluewin-Spam-Score: 0.00 X-FXIT-IP: IPv4[84.227.21.131] Epoch[1732067082] X-Bluewin-AuthAs: public0x05bf@bluewin.ch Received: from 10.235.1.189 (SquirrelMail authenticated user public0x05bf) by main with HTTP; Wed, 20 Nov 2024 02:28:39 +0100 Message-ID: <16c198593dc27302ab90ca7fe39bb71c.squirrel@main> Date: Wed, 20 Nov 2024 02:28:39 +0100 Subject: (Re ** 6)[1]: Extending "thin_trim" (about pseudo-raid: Why!) From: =?iso-8859-1?Q?=22Thomas_Br=FCcker=22?= To: "Zdenek Kabelac" , dm-devel@lists.linux.dev User-Agent: SquirrelMail/1.4.21 Precedence: bulk X-Mailing-List: dm-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain;charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Priority: 3 (Normal) Importance: Normal X-CMAE-Envelope: MS4xfKB5hU+3sM+cLKo9onaSJBI/886VIvUXShNe0/8vK3p2kQgVgboC1Ts7tceHNVFstHLllXxq6T4vlx/XxjLPRgznzi6bBOb+tV+9tBMmMJRHDZvG83/w CPvk6W7rEAKB/OKFT7ZdNjfaq8TdqAFsZ9ELvF/te2xQCai0DmOnZucX6BvR8L12nM/ja9TXWqsTb5VmtjeGuxNTV1dPtvZwXaXpN/FOxvVwZi22AIXx+fyo Xl/SbOAKjF7TRhH8htq/AF+tr/si6ftYVWs1lzSxmPA= Dear Mr. Kabelac, * I have had two (real!) cases which three mechanical harddisks, that have had defective sectors (within warranty time!), not just announced as defective, but really unreadable. 1st case: Two ecolocical, energy saving samsung disks, that have both got unreadable sectors, happyly mutually not on the same location, connected as raid1: All data could be read and saved. 2nd case: An usb-disk that had got unreadable sectors with a 'pseudo-raid' on it: All data could be read and saved. * Experimental case: Test of 'pseudo-raid' on a dvd, the dvd was scratched and could partially not be read: The pseudo raid could be read without any problem ( * ok. if the metadata on the dvd, which is responsible to have access to the dvd at all, is scratched, you loose everything. * about a read-only!-dvd with 'raid' on it ...: I use another 'strange' construct with dm-target dm-snapshot to protect the dvd from writing to. ). * I have had at least two (real) cases of harddisks with each having a unreadable first sector (== the partition table): The laptops could neither been started, nor could the data.been accessed, After rewriting the partition table, the disks worked just long enough, to copy a complete image of them. (either the disk has a partiton at the 'usual' location, or you may search for the begin of the filesystem...) * Link (I don't want to attach and clutter your mail server with unneces- sary images) to: Defective disk in harddisk device. "http://www.thomas-r-bruecker.ch/favorites/io/disk/Defective_disk.jpg". (It begins mostly with defective sectors and ends in a crash.) * So, for me, it is a good idea, to protect myself from defective sectors. * 'Normal' raid(1): * notebooks with two harddisks in it ...? * travelling with a laptop and two usb-harddisks ...? Sincerely Thomas ============================================================================ On Tue, November 19, 2024 2:37 pm, Zdenek Kabelac wrote: > Dne 19. 11. 24 v 3:11 "Thomas Bruecker" napsal(a): >> ]...] > [...] > And while I can 'see' a small value in having the same data stored > multiple times on the same drive - the protection you get from this is > close to nothing > [...] > With prices of storage these days I'd simply recommend to simply use the > raid the way it's supposed to be used. > [...]