From mboxrd@z Thu Jan 1 00:00:00 1970 From: Max Waterman Subject: Re: raidreconfig advice Date: Thu, 28 Jul 2005 10:28:05 +0800 Message-ID: References: <4232B49C.6080306@fastmail.co.uk> <42331AC6.6050109@h3c.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <42331AC6.6050109@h3c.com> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Mike Hardy wrote: > > > Max Waterman wrote: > >> OK, I am going to try to expand the capacity of my raid5 array and I >> want to make sure I've got it right. > > > Not a bad idea, as its all or nothing... > >> Disk /dev/hdg: 200.0 GB, 200049647616 bytes >> Disk /dev/hdi: 200.0 GB, 200049647616 bytes >> Disk /dev/hdk: 200.0 GB, 200049647616 bytes >> Disk /dev/sda: 200.0 GB, 200049647616 bytes >> Disk /dev/sdb: 200.0 GB, 200049647616 bytes >> Disk /dev/sdc: 200.0 GB, 200049647616 bytes >> Disk /dev/sdd: 200.0 GB, 200049647616 bytes > > > They certainly all looked the same (including the C/H/S counts) > >> This leaves me with sdc which I can try to add. If that goes OK, I'll >> trash the backup and add sd[ab] too. > > > I'd be very wary of this, for two reasons. One, you have the backup > during the add for a reason. If anything goes wrong, there goes your > data. Second, where would you ever back your raid up to? What about fs > corruption? > > The rule of thumb with databases is to always have enough contiguous > scratch space to dump and restore your biggest table. With large RAID, > you should always be able to dump and restore your largest raid device, > imho. Its a bunch more disk yes, but you'll need it at some point, I > promise. Many future tears can be averted... I'm not worried about losing my data enough to make regular backups. I recently thought I'd lost all my data - it wasn't that much of a shock. I since discovered I hadn't lost it all, so all is well. I've made a backup onto a spare array, plus onto one of the 200GB disks which I will use as a spare later. > >> 3) Are there any instructions for raidreconfig? I understand is uses >> some non-mdadm config files as from/to input. > > > the man page is great - honest. Two conf files (current and future) and > you're set Yeah, but I don't know how to use raidconf files. I use mdadm. I currently have in my mdadm.conf : DEVICE /dev/hd[egik] ARRAY /dev/md0 level=raid5 num-devices=4 devices=/dev/hd[egik] I think my target mdadm.conf would be : DEVICE /dev/hd[egik] /dev/sd[abc] ARRAY /dev/md0 level=raid5 num-devices=7 devices=/dev/hd[egik],/dev/sd[abc] What are these in raidtab(5) terms? Max.