From: Tomasz Pala <gotar@polanet.pl>
To: "Majordomo vger.kernel.org" <linux-btrfs@vger.kernel.org>
Subject: Re: degraded permanent mount option
Date: Tue, 30 Jan 2018 17:22:55 +0100 [thread overview]
Message-ID: <20180130162255.GA28192@polanet.pl> (raw)
In-Reply-To: <20180130150950.GB7126@polanet.pl>
On Tue, Jan 30, 2018 at 16:09:50 +0100, Tomasz Pala wrote:
>> BCP for over a
>> decade has been to put multipathing at the bottom, then crypto, then
>> software RAID, than LVM, and then whatever filesystem you're using.
>
> Really? Let's enumerate some caveats of this:
>
> - crypto below software RAID means double-encryption (wasted CPU),
>
> - RAID below LVM means you're stuck with the same RAID-profile for all
> the VGs. What if I want 3-way RAID1+0 for crucial data, RAID1 for
> system and RAID0 for various system caches (like ccache on software
> builder machine) or transient LVM-level snapshots.
>
> - RAID below filesystem means loosing btrfs-RAID extra functionality,
> like recovering data from different mirror when CRC mismatch happens,
>
> - crypto below LVN means encrypting everything, including data that is
> not sensitive - more CPU wasted,
And, what is much worse - encrypting everything using the same secret.
BIG show-stopper.
I would shred such BCP as ineffective and insecure for both, data
integrity and confidentiality.
> - RAID below LVM means no way to use SSD acceleration of part of the HDD
> space using MD write-mostly functionality.
--
Tomasz Pala <gotar@pld-linux.org>
next prev parent reply other threads:[~2018-01-30 16:22 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-26 14:02 degraded permanent mount option Christophe Yayon
2018-01-26 14:18 ` Austin S. Hemmelgarn
2018-01-26 14:47 ` Christophe Yayon
2018-01-26 14:55 ` Austin S. Hemmelgarn
2018-01-27 5:50 ` Andrei Borzenkov
[not found] ` <1517035210.1252874.1249880112.19FABD13@webmail.messagingengine.com>
2018-01-27 6:43 ` Andrei Borzenkov
2018-01-27 6:48 ` Christophe Yayon
2018-01-27 10:08 ` Christophe Yayon
2018-01-27 10:26 ` Andrei Borzenkov
2018-01-27 11:06 ` Tomasz Pala
2018-01-27 13:26 ` Adam Borowski
2018-01-27 14:36 ` Goffredo Baroncelli
2018-01-27 15:38 ` Adam Borowski
2018-01-27 15:22 ` Duncan
2018-01-28 0:39 ` Tomasz Pala
2018-01-28 20:02 ` Chris Murphy
2018-01-28 22:39 ` Tomasz Pala
2018-01-29 0:00 ` Chris Murphy
2018-01-29 8:54 ` Tomasz Pala
2018-01-29 11:24 ` Adam Borowski
2018-01-29 13:05 ` Austin S. Hemmelgarn
2018-01-30 13:46 ` Tomasz Pala
2018-01-30 15:05 ` Austin S. Hemmelgarn
2018-01-30 16:07 ` Tomasz Pala
2018-01-29 17:58 ` Andrei Borzenkov
2018-01-29 19:00 ` Austin S. Hemmelgarn
2018-01-29 21:54 ` waxhead
2018-01-30 13:46 ` Austin S. Hemmelgarn
2018-01-30 19:50 ` Tomasz Pala
2018-01-30 20:40 ` Austin S. Hemmelgarn
2018-01-30 15:24 ` Tomasz Pala
2018-01-30 13:36 ` Tomasz Pala
2018-01-30 4:44 ` Chris Murphy
2018-01-30 15:40 ` Tomasz Pala
2018-01-28 8:06 ` Andrei Borzenkov
2018-01-28 10:27 ` Tomasz Pala
2018-01-28 15:57 ` Duncan
2018-01-28 16:51 ` Andrei Borzenkov
2018-01-28 20:28 ` Chris Murphy
2018-01-28 23:13 ` Tomasz Pala
2018-01-27 21:12 ` Chris Murphy
2018-01-28 0:16 ` Tomasz Pala
2018-01-27 22:42 ` Tomasz Pala
2018-01-29 13:42 ` Austin S. Hemmelgarn
2018-01-30 15:09 ` Tomasz Pala
2018-01-30 16:22 ` Tomasz Pala [this message]
2018-01-30 16:30 ` Austin S. Hemmelgarn
2018-01-30 19:24 ` Tomasz Pala
2018-01-30 19:40 ` Tomasz Pala
2018-01-27 20:57 ` Chris Murphy
2018-01-28 0:00 ` Tomasz Pala
2018-01-28 10:43 ` Tomasz Pala
2018-01-26 21:54 ` Chris Murphy
2018-01-26 22:03 ` Christophe Yayon
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