From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from vps.thesusis.net (vps.thesusis.net [34.202.238.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 96618132804 for ; Tue, 25 Jun 2024 19:00:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=34.202.238.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719342042; cv=none; b=P8dOfKbRpkP625DCdXgTXbw5HdkNiDJTAh1u0RilZqdiZzL712wWGKfBxg+H5aO7M9nQFlBAq09taLS+ha4B6W1YQwd/ICNdFK+yzmv73RByzabZ6QW7rNQzBDLKVGOeg9yJFqpm2vUWgXql4juhCkW9R7SLBtHm3Wds3CCuaGI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719342042; c=relaxed/simple; bh=n4JtvSqiQt0AHR2yMYUAewvDm9jELWTaiqvOoBG042c=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=Kk4mpKZFHsfRkYBF1jYBsY2GHt5zj5KFLJGiuxYBHzon4kbGvjofD2yIOZhI2ufqyRhWQQN/AydVJOhU7LyAp5DxiCwU8QpAh6wzFqiav75xp7lCzgOFfEKt/dvd9K+Jm3i8u56qG5WyIbLTumS6SzPZu4LOVVoucMg7YXMkoSE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=thesusis.net; spf=pass smtp.mailfrom=thesusis.net; arc=none smtp.client-ip=34.202.238.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=thesusis.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=thesusis.net Received: by vps.thesusis.net (Postfix, from userid 1000) id B0AC43C447; Tue, 25 Jun 2024 15:00:39 -0400 (EDT) From: Phillip Susi To: Piergiorgio Sartor , Reindl Harald Cc: Piergiorgio Sartor , linux-raid@vger.kernel.org Subject: Re: RAID-10 near vs. RAID-1 In-Reply-To: References: Date: Tue, 25 Jun 2024 15:00:39 -0400 Message-ID: <87ikxw6e5k.fsf@vps.thesusis.net> Precedence: bulk X-Mailing-List: linux-raid@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Piergiorgio Sartor writes: > As far as I know, but please correct me if > I'm wrong, a Linux md RAID-10 *near* layout, > with 2 devices, has identical data distribution > as a RAID-1 with 2 devices. > Meaning the 2 devices are a mirror. That's correct. > The difference, if I understood it correctly, > is that the RAID-10 has chunks, and hence stripes, > while the RAID-1 does not have stripes. > Furthermore, the read operation on RAID-10 are > interleaved, delivering (for SSDs) double > sequential read speed (for 2 devices), while > the RAID-1 can handle two independent (one per > device) read stream, each with single device > reading speed. No, since the layout is exactly the same as raid1, large sequential reads can not be sent to both drives at the same time. Now a two disk raid-10 in the offset or far layout however, does interleave the data across the drives so they can both be read at the same time to increase throughput.