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[213.175.37.10]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3825494ca3fsm1682729f8f.111.2024.11.20.02.42.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 20 Nov 2024 02:42:21 -0800 (PST) From: Zdenek Kabelac X-Google-Original-From: Zdenek Kabelac Message-ID: <91d94f48-bae4-48eb-8604-a7522f7062c8@redhat.com> Date: Wed, 20 Nov 2024 11:42:20 +0100 Precedence: bulk X-Mailing-List: dm-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: (Re ** 6)[1]: Extending "thin_trim" (about pseudo-raid: Why!) To: =?UTF-8?Q?Thomas_Br=C3=BCcker?= , Zdenek Kabelac , dm-devel@lists.linux.dev References: <16c198593dc27302ab90ca7fe39bb71c.squirrel@main> Content-Language: en-US, cs In-Reply-To: <16c198593dc27302ab90ca7fe39bb71c.squirrel@main> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Dne 20. 11. 24 v 2:28 "Thomas Brücker" napsal(a): > 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. Hi Any device that is showing  'error' sectors (aka  smartctl shows badblocks, uncorrectable errors)   should be ASAP 'recovered/copied' to another new disk - and such faulty disk should no longer be used for anything you care about! If you think  the disk is still 'good enough' to not be thrown to trash/recycle bin -  you could probably do a surface analysis - and i.e. allocate partitions on a drive in such a way that HUGE portion of drive before and after the error  is left  as not being used/allocated   (works for HDD -   for SSD/NVMe this obviously makes no sense) -  so then HDD reading heads are not damaging those errori places any more - and then you can try to use it to store something unimportant - i.e.  3rd. backup of something.... Using faulty drive as 'daily work  disk'  with the idea you've 'saved' something  makes no sense - you are just preparing yourself big troubles.... > * 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 ( Just backup all your DVDs on TiB drives  while they are still readable.... > > * I have had at least two (real) cases of harddisks with each having a > unreadable first sector (== the partition table): The laptops could > neither Such drives are simply an electronic waste for recycling... > * 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 ...? Seriously you should really use real  raid1 instead of these rather highly 'questionable' data protection ideas...  (if you care about your data) And yes - all notebooks I know  have at least  2 slots for drives - one is typically equipped when being sold - other one is usually empty - one just has to dismount laptop cover and add the drive to unused slot... Regards Zdenek