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From: Joe Thornber <thornber@redhat.com>
To: LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] when bringing dm-cache online, consumes all memory and reboots
Date: Mon, 23 Mar 2020 08:26:08 +0000	[thread overview]
Message-ID: <20200323082608.7i6wzq2t3k24hzun@reti> (raw)
In-Reply-To: <CACRKOwz_fOJiTVhbUqJR_EaxrKbf2bk+wb6LYOy0yWDkvt+buw@mail.gmail.com>

On Sun, Mar 22, 2020 at 10:57:35AM -0700, Scott Mcdermott wrote:
> have a 931.5 GibiByte SSD pair in raid1 (mdraid) as cache LV for a
> data LV on 1.8 TebiByte raid1 (mdraid) pair of larger spinning disk.
> these disks are hosted by a small 4GB big.little ARM system
> running4.4.192-rk3399 (armbian 5.98 bionic).  parameters were set
> with: lvconvert --type cache --cachemode writeback --cachepolicy smq
> --cachesettings migration_threshold=10000000

If you crash then the cache assumes all blocks are dirty and performs
a full writeback.  You have set the migration_threshold extremely high
so I think this writeback process is just submitting far too much io at once.

Bring it down to around 2048 and try again.

- Joe

  reply	other threads:[~2020-03-23  8:26 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-22 17:57 Scott Mcdermott
2020-03-23  8:26 ` Joe Thornber [this message]
2020-03-23  9:57   ` Zdenek Kabelac
2020-03-23 16:26     ` John Stoffel
2020-03-23 22:02     ` Scott Mcdermott
2020-03-24  9:43       ` Zdenek Kabelac
2020-03-24 11:37         ` Gionatan Danti
2020-03-24 15:09           ` Zdenek Kabelac
2020-03-24 22:35             ` Gionatan Danti
2020-03-25  8:55               ` Zdenek Kabelac
2020-03-23 21:35   ` Scott Mcdermott

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