From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Pittman Subject: Re: number of global spares? Date: Sat, 27 Aug 2005 15:00:28 +1000 Message-ID: <87u0hc55zn.fsf@rimspace.net> References: <1125082848.25483.23.camel@seki.nac.uci.edu> <200508262321.j7QNLuE03756@www.watkins-home.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids "Guy" writes: [...] >> I've been working on a RAID setup with dual RAID controllers and >> three expansion boxes - 48 disks in all, including data, parity and >> global spares. [...] >> They don't feel that the storage has to be blazing fast, and 100% uptime >> isn't paramount, however they very much do not want to lose their data. >> >> The filesystem will not be backed up - we simply don't have anything large >> enough to back it up -to-, so if the some part of the storage solution >> goes kerflooey, we're totally... er... out of luck, and they'll probably >> be looking at me (the primary sysadmin on the storage configuration), >> wondering why their data is gone. > > RAID5, 6 or 1 is not data backup! It is hardware redundancy!! > Data loss or corruption can still occur with a RAID solution. RAID won't > help if someone fat fingers a "rm" command. > Corruption of the filesystem can also cause major data loss, without a > failed disk. > > If the data was lost, what would it cost to re-create it? > Enough to buy a backup system? I absolutely agree with this. When - and it is when, not if - the content of this filesystem goes away, you will be rightly blamed for it. Invest the few thousand dollars in a good high capacity tape drive and pay someone to change the tapes. This will be worth it when the system finally does fail in some nasty, unpredictable way! Daniel