From: "Swâmi Petaramesh" <swami@petaramesh.org>
To: linux-btrfs@vger.kernel.org
Subject: How to make BTRFS crawl
Date: Fri, 11 Apr 2014 11:42:23 +0200 [thread overview]
Message-ID: <4171851.75rN5oGIof@zafu> (raw)
Hi,
I was asked about situations "use cases" that would cause BTRFS to slow down
to a crawl.
And it's exactly what happened to me yesterday when I was trying, on the
contrary, to speed it up.
So here's the recipe for getting a "slow to the point it is unusable" BTRFS.
1/ Perform a clean, fresh install of a recent distro with a 3.13 kernel (i.e.
Fedora 20) and a BTRFS root filesystem.
2/ Choose the version with a KDE interface
3/ Configure fstab mountpoints using such options (space_cache will have been
manually activated once):
/ btrfs subvol=FEDORA,noatime,compress=lzo,autodefrag
/home btrfs subvol=HOME,noatime,compress=lzo,autodefrag
4/ Use "chattr +C" to make the following directories NOCOW (move the old
directory elsewhere, create a new dir, make it nocow, copy files from the old
one so they are recreated with nocow, check permissions...):
- /home/yourself/.cache
- /home/yourself/.local/share/akonadi
5/ Use IMAP mail in Kmail. Seriously process your email (it will be stored
using akonadi mysql)
6/ Surf normally the web using Firefox
7/ Install SuSE "snapper" package that will perform a FS snapshot every hour.
Configure it so it will snapshot both the root FS subvol and the /home subvol
8/ Use the system for 24 hours and you will know that "hardly usable" means...
Especially every hour-on-the-hour when Kmail or Firefox will try to access
files that have been recently snapshotted... Your system will be dead with
saturated HD access for several *minutes*
...Hope this may help hunting this down...
Kind regards.
--
Swâmi Petaramesh <swami@petaramesh.org> http://petaramesh.org PGP 9076E32E
next reply other threads:[~2014-04-11 9:42 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-11 9:42 Swâmi Petaramesh [this message]
2014-04-11 14:11 ` How to make BTRFS crawl George Mitchell
2014-04-11 15:29 ` Hugo Mills
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