From: Marcin Wolcendorf <antymat+redhat@chelmska.waw.pl>
To: linux-lvm@redhat.com
Subject: [linux-lvm] lvmcache writethrough synchronisation at system startup
Date: Wed, 5 Dec 2018 07:19:38 +0100 [thread overview]
Message-ID: <20181205061938.vbkwk6ydnehacxml@chelmska.waw.pl> (raw)
[-- Attachment #1: Type: text/plain, Size: 1280 bytes --]
Hi Everyone,
Recently I have set up a simple lvmcache on my machine. This is a write-through
cache, so in my view it should never be necessary to copy data from the
cachepool to the origin LV. But this is exactly what happens: on system start
the
lvs -o+cache_policy,cache_settings,cache_mode
displays something like:
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert CachePolicy CacheSettings CacheMode
home main Cwi-aoC--- 21.83t [cache1] [home_corig] 99.99 0.55 90.39 smq writethrough
and for a next day or two it writes the whole cachepool to the origin. The data
on the cached LV seems fine as long as sha512 is concerned.
Is this supposed to be that way?
My setup:
I have 2 mdraid devices: one 24T raid6, one 1T raid1, and one separate SSD. All
are LUKS-encrypted, SSD is partitioned into MBR boot partition, encrypted /boot
partition and a big encrypted partition for a PV. The encrypted block devices
(except /boot) are PVs in my VG. The 24T RAID holds the origin LV, the 1T RAID
is made into a cachepool.
BR,
M.W.
--
On a paper submitted by a physicist colleague:
"This isn't right. This isn't even wrong."
-- Wolfgang Pauli
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
next reply other threads:[~2018-12-05 6:20 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-05 6:19 Marcin Wolcendorf [this message]
2018-12-05 14:23 ` [linux-lvm] lvmcache writethrough synchronisation at system startup Zdenek Kabelac
2018-12-05 15:01 ` Marcin Wolcendorf
2018-12-06 11:32 ` Zdenek Kabelac
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20181205061938.vbkwk6ydnehacxml@chelmska.waw.pl \
--to=antymat+redhat@chelmska.waw.pl \
--cc=linux-lvm@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).