From mboxrd@z Thu Jan 1 00:00:00 1970 From: jim owens Subject: Re: New idea about RAID and SSD Date: Tue, 01 Sep 2009 09:10:21 -0400 Message-ID: <4A9D1D3D.2070003@hp.com> References: <4A9D1746.1020407@mmmm.it> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Cc: linux-btrfs@vger.kernel.org To: Massimo Maggi Return-path: In-Reply-To: <4A9D1746.1020407@mmmm.it> List-ID: Massimo Maggi wrote: > Hi, > SSDs have low latency but a high price per GB, > Traditional hard disks have high latency, but high sequential read/write > speed and low price per GB. > Is possibile to use a SSD for metadata, which requires many seeks and is > relatively small, in a special "RAID mode" with a traditional hard disk > for the extents of the real data? > A cheap but performant SSD (maybe 32 GB) + a big and fast HD (maybe 1.5 > TB, or two in RAID0 - 3TB ), wouldn't create an array much cheaper than > a ssd-only array of the same size, and much faster (in > not-only-sequential workload) than one or two traditional HDs in RAID0? > Would it work? > Thank you for your precious time! > Massimo Maggi > massimo@mmmm.it well, it is not a "new" idea. yes people are thinking about it, but it is not the most critical work on the list of things to do for btrfs or any other linux fs. jim