From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Anderson-Lee Subject: Re: petabyte class archival filestore wanted/proposed Date: Thu, 22 Jun 2006 11:58:48 -0700 Message-ID: <449AE868.2040500@eecs.berkeley.edu> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-fsdevel@vger.kernel.org Return-path: Received: from gateway0.EECS.Berkeley.EDU ([169.229.60.93]:51074 "EHLO gateway0.EECS.Berkeley.EDU") by vger.kernel.org with ESMTP id S1161200AbWFVS6f (ORCPT ); Thu, 22 Jun 2006 14:58:35 -0400 To: Bryan Henderson In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Bryan Henderson wrote: >> 1) Tapeless: maintain multiple copies on disk (minimize >>backup/restore lag) >> >> >Can you really call it archival if you're willing to pay 5 times as much >for quick access? Maybe you need a different word. Archive means large >quantities of data with very low access frequency. And sometimes, in the >current legal climate, with very low chance of destruction. > >You word this as if the only potential use of tape is backup of disk-based >data, but it's also pretty useful as the primary copy of archival data. > > I know some people swear by them, but our experience with tertiary (tape and optical) storge systems has never been positive. (We have tried several over the years, from several vendors.) Leave it at that, and let's just say we want to explore new territory. There is also an argument that the cost of tape and disk is slowly converging/crossing. Some disagree, we find it an interesting point. For many users, the cost of archival storage is often dominated by non-hardware costs. Our internal departmental recharge rates for (tape) backed-up storage are on the order of $5/month to $10/month per GIGABYTE of storage. That's $60/GB/year to $120/GB/year. Very little of that cost is hardware. Considering that a GB of disk now costs $1 to $2 for commodity disks, I can afford to keep several copies of my data online for quick access when I do want it, especially when it is mostly archival and doesn't change that often (almost never). Jeff Anderson-Lee Petabyte Storage Infrastructure Project University of California Berkeley