From: Chris Murphy <lists@colorremedies.com>
To: Marc MERLIN <marc@merlins.org>
Cc: d tbsky <tbskyd@gmail.com>, list Linux RAID <linux-raid@vger.kernel.org>
Subject: Re: new drive is 4 sectors shorter, can it be used for swraid5 array?
Date: Mon, 28 Mar 2022 18:13:42 -0600 [thread overview]
Message-ID: <CAJCQCtQyqG_zWhRVXjnc3Prc+J-7hK1hyp28mwyuKWWPJ8Uo5A@mail.gmail.com> (raw)
In-Reply-To: <20220328020512.GP4113@merlins.org>
On Sun, Mar 27, 2022 at 8:05 PM Marc MERLIN <marc@merlins.org> wrote:
>
> OMG, using a USB adapter eats 4 setors? I had no idea...
> Sure enough, I did connect the drives via USB for diagnosis since I had
> run out of sata ports.
None of my SATA-USB enclosures behave this way. But what it does do is
mask (lie) the true physical sector size, claiming it's 512 bytes
instead of 4096 bytes.
I've also seen enclosures turn a 512 byte logical sector drive into a
4096 byte logical sector drive, which is a real PITA because it
completely messes up the GPT. My understanding of the logic of GPT
format is atomic modifications that are crash safe (that's up to the
tool to do correctly too but the spec has a pretty specific order each
sector is supposed to be written), but in practice this is another
PITA for a significant minority of users who end up putting an
internal drive into an enclosure and bam - can't read the drive at
all.
It'd be kinda neat if this condition could be detected and have a
device mapper target setup to deal with it.
--
Chris Murphy
next prev parent reply other threads:[~2022-03-29 0:14 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-18 3:08 new drive is 4 sectors shorter, can it be used for swraid5 array? Marc MERLIN
2022-03-18 7:54 ` Wols Lists
2022-03-18 12:30 ` Roman Mamedov
2022-03-19 4:10 ` Marc MERLIN
2022-03-19 10:14 ` Wols Lists
2022-03-19 22:02 ` Marc MERLIN
2022-03-21 19:35 ` Nix
2022-03-19 10:45 ` Roman Mamedov
2022-03-26 18:01 ` Tom Mitchell
2022-03-26 18:29 ` Wols Lists
2022-03-27 8:40 ` d tbsky
2022-03-28 2:05 ` Marc MERLIN
2022-03-29 0:13 ` Chris Murphy [this message]
2022-03-29 1:55 ` d tbsky
2022-03-30 2:33 ` Andy Smith
2022-04-02 12:48 ` d tbsky
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