On Sat, September 4, 2010 10:24, Stroller wrote: > > On 4 Sep 2010, at 13:15, Raymond Kolbe wrote: >> ... 1) Create a Ghost image of OS/data, etc. for backup and restore. 2) >> Turn off the server and replace both drives with the newer 300GB >> drives. 3) Turn on the server and create a new RAID1 array. 4) Restore >> the Ghost image from step 1. 5) Use gParted or another partition >> resizing program to increase my partitions. >> >> However, no one has confirmed that these methods worked for them. >> >> Now, both ways sound like they would work, but I am extremely nervous >> about this because I have also found forum postings and articles about >> having to manually copy over partition information, and that disk block >> sizes matter, etc. (not exactly sure about the technical issues here), >> etc. This is also a mission critical production server so uptime is >> key. >> >> So my question is, are either of the two methods above realistic, >> and/or has anyone actually upgraded RAID1 in a PE2850 or PE server >> before without having to reinstall their OS? > > > I've definitely done this sort of thing with another model of PowerEdge, > the 2800. I think I've done it with a 2850, although mine doesn't have > the RAID key. > > The drives will just appear to the o/s as block devices - if you boot > from a LiveCD (well, as long as it's one that supports the RAID > controller) you'll see the current array as (something like) /dev/sda. > Take a note of the current configuration, just so you're completely > confident (e.g. `ls -l /dev/disk/* > /mnt/floppy/file.txt`). > > Shutdown the system, slap the new drives in (don't remove the existing > ones), create an array of them in the RAID BIOS, and reboot again to the > Live CD. You'll see the existing /dev/sda as it was before (compare > /dev/disk/by-id/* with what you had before) and a new /dev/ sdb. The RAID > controller consolidates the drives (hardware RAID) and presents them to > the o/s as the single /dev/sdb block device. > > You can simply `dd if=/dev/sda of=/dev/sdb`, shutdown the system, remove > the original array, power up and change the boot device in the RAID BIOS > and boot to the cloned system. > > I personally don't use Ghost - Linux has `dd` which is perfectly > adequate. I trust it more than Ghost. You can "ghost" to backup image > file on an external USB drive with `dd if=/dev/sda of=/mnt/seagate/ > file.img`. Nor do I use gParted, but the command-line parted. `sudo > parted /dev/sda p` should show that the new array is larger. It can be a > pain to manipulate in Linux the partitions of Windows Server, as I've > mentioned in the past. > > I'm tending to assume 2 system drives in a RAID1 here, so that you have > enough empty bays for the two replacement disks. You can unmount and > remove data arrays whilst you're upgrading the system drives. I perform > all partition / filesystem resizes from the LiveCD, with the disks > unmounted. > > DON'T do this sort of thing on a production system without a backup. This > mailing-list posting confers no warranty, express or implied. If, like > me, you're a lone IT consultant working on a client's only > mission-critical server (or even one of your own) this kinda stuff can be > tremendously stressful. There is potential for you to foul-up at any time > if you just once confuse your source and destination drives. > > This demonstrates the need for backups constantly throughout the system's > life - really, as soon as you've commissioned the system you should be > taking backups, you should test them; you should do a full restore just > to prove you can, before you have any important data on there. Of course > there are many occasions when we are not so perfect, but this migration > is perfectly manageable if you're careful; 99 times out of 100 there will > be no problems, but it can be a bit nerve- wracking. > > You ought to be confident about this before you start, so if you can't > get (or afford) someone more experienced to help then my best > recommendation is to practice it on another system first. I got my 2850 > at least 6 months ago, and they were going for less than £200 on eBay > then - I wouldn't be surprised if they're less than £100 now. > > This is a really straightforward migration that most of the guys on this > list - or any other experienced Linux system administrator - would have > no trouble at all with. I'm surprised you can't find "confirmation" of > this working (although I think few of us would use Ghost, if that's part > of your search criteria) because I think there are probably people doing > this on a daily basis with no problems. But one can't write exact > instructions for you at one remove like this - the block devices may be > named differently on your system, for example as /dev/hda instead of > /dev/sda, and of course there's the liability that a single tiny omission > can foul you up. But, yes, this technique, generally speaking, does work. >
I can vet pretty much everything Stroller says, have done a number of variations of this, often using g4l (Sourceforge) which just glues together a live CD, dd, compression, and ncftp to put the compressed image on an ftp server. When restoring to larger array I've sometimes ended up with a partition table that no partition editor could stomach modifying but IIRC that's only happened with RAID5 (shouldn't matter, I know, but I don't think I've seen it on a RAID1). If you know what you're doing and have preserved a partition map to refer to you can delete the table under those circumstances and build a new one without initializing anything and come out ok. You can also avoid by manually partitioning the new array and copying sda1-->sdb1 etc and doing a grub-install or copying the MBR to make bootable. Finally, although I've been slicing/dicing disk partitions from the command line since HPUX v4, I like Partedmagic for a lazy man's toolkit to move/resize partitions. But I wouldn't use it if I didn't know how to get under the hood and hotwire things if it left me in the lurch. _______________________________________________ Linux-PowerEdge mailing list [email protected] https://lists.us.dell.com/mailman/listinfo/linux-poweredge Please read the FAQ at http://lists.us.dell.com/faq
