From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Heide Subject: write-mostly vs. write-behind Date: Thu, 18 Jul 2013 09:25:10 +0200 Message-ID: <20130718092510.6f4a6fd6@tbb-phenom> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Hi, the md manpage says there are write-mostly and write-behind options for md raid1 and you can use write-behind on devices where write-mostly is activated. I'm using a small low-power home-server with a HDD and an usb flash drive, where one HDD partition (with important data) is mirrored (raid1) to the flash drive. (other data is not that important) The flash drive (usb-stick / pen-drive / usb-key) is faster in reads and slower in writes than the HDD. So read requests are slow because of the slower HDD and write requests are even slower because of the slow flash drive. I would like to use "write-mostly" with the HDD and "write-behind" with the flash drive. That's impossible with Linux MD Raids, right? Regards Michael (I'm not subscribed)