From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mimecast-mx02.redhat.com (mimecast05.extmail.prod.ext.rdu2.redhat.com [10.11.55.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3920E2166B2C for ; Mon, 16 Dec 2019 08:23:03 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [205.139.110.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 306BB8012D3 for ; Mon, 16 Dec 2019 08:23:03 +0000 (UTC) From: Daniel Janzon Date: Mon, 16 Dec 2019 08:22:56 +0000 Message-ID: Content-Language: en-US MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [linux-lvm] Best way to run LVM over multiple SW RAIDs? Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii" To: "linux-lvm@redhat.com" > From: Guoqing Jiang >>On 12/7/19 11:44 PM, John Stoffel wrote: >> As Daniel says, he's got lots of disk load, but plenty of CPU, so the >> single thread for RAID5 is a big bottleneck. >Perhaps set "/sys/block/mdx/md/group_thread_cnt" could help here, Now I finally had a chance to test this. It turns out to work great! It's not as fast as a non-raided linearly allocated LVM volume (about half of performance without getting a fat tail of high read/write response time). So there is a price for redundancy but that is worth it in my application. It's now up there in the same magnitude. Thanks a lot Guoqing! You really helped me a lot here. I'd also like to thank John Stoffel for valuable input.