On Fri, 27 Jun 2003, James Melin wrote: > I have been reviewing the start/stop functions within the various rcx.d > entries and I think I have a handle on this....but I want to run this past > the reflecting pool of wisdom known as the Linux-390 list. > > What I believe I need to do in order to get my boulder sized backups > without taking the linux LPAR all the way down/up is this: > > Change to runlevel 2, and let the system handle getting various things down > through normal channels. > > Runlevel 2 is going to start the following, by default (not sorted by > number - sorry) > > S02dhclient > S10at > S05network > S10mysql > S07route > S10quota > S08proftpd > S10raw > S08snmpd > S11lpd > S01SuSEfirewall_init > S08syslog > S11smbfs > S01dummy > S10acct > S11xntpd > S01random > S10argus > S12cron > > My question is this: Where does telnet get started, will it stay active > through a runlevel 3-2 shift and if not how does one start it. Secondly, > since I don't use the SuSE Firewall, is there a point to me having this in > rc2.d? I also wont need the SMBFS or mysql started. I'm just loathe to > remove things from rc2.d since they are 'stock' and would be replaced in an > OS upgrade
Those are (almost certainly) symlinks and they should not be changed with a system upgrade. > > Why runlevel 2? I want everything to halt so I can run a script that will > take the file systems one by one and mount them read only and initiate a dd > disk copy to a matching set of spare volumes. I'm not sure that I want the > system in single user mode, since our operators really don't have anythign > to do with this, and I want to be able to telnet into the box if I have to > dial into work to fix things. > > Once the dasd has been mirrored, I want to take it offline to linux, send > the system back to runlevel 3 and continue on. The one problem I'm having > is with a component of DB2 connect coming up. I have had to manually issue > db2start from the db2inst1 ID after the system is up, so I also need to > know if it's possible for a script to do an su to the db2inst1 ID and still > issue a command when it's time to bring the system back to runlevel 3 > > any examples of unix shell scripts that do things like this I could see > would be most helpful. > > All this for lack of a backup client that doesn't suck, since I cant play > in the 3494 because nobody here trusts linux/amanda to handle it properly > I think you should be using LVM for omportant disks. One of its capabilities is to lock down the state of the filesystem as at when you start your backup. You might still need to stop everything so as to get files closed, but one the backup is started (with the LVM tools), you can then start things again. That aside, I would evaluate an alternative to dd for backing up your disk space. dd takes full copies of all specified disks whether anything's changed or not, whether the disk is used at all or full. In contrast, rsync copies only those files that are changed. If no files have been changed, it completes quite quickly. The thing to watch out for with rsync is CPU usage. Evaluate whether you prefer the amount of CPU power it uses over the disk I/O it doesn't do. There is also dump. dump understands the filesystem internals, and dumps only the data that's there, Then there are tar, pax, cpio and afio (maybe more), all with their place in the scheme of things. All have the advantage over dd that they backup files, not filesystems, and so in some circumstances are faster than dd. Because dump understands the filesystem structures, it can be faster than those on real disks because, like dd, it reduces seeking. An important difference between dd and the rest is that dd clones your disk space, whereas the others copy your data. A backup/restore operation using those (possibly excepting dump/restore in some cases) eliminates any possible fragmentation, allows you to change filesystem types between any supported by Linux, allows you to resize/restructure filesystems. You should also check out the capabilities of your dasd devices. I gather some have the ability to clone volumes, and can do it pretty-much instantly. Finally, some files are best backed up with special tools. If you are using database software (I suspect db2connect doesn't count here, but I may be wrong), check what its authors recommend. Back when I was the ADABAS guru, the ADABAS backup program did more than just backup the data (and could do it without taking MPM down). Grand finally, consider software RAID and similar across the LAN. This allows you to mirror volues remotely. You get most of the benefits of having whole filesystem backups without taking the system down for maintenance. -- Cheers John. Join the "Linux Support by Small Businesses" list at http://mail.computerdatasafe.com.au/mailman/listinfo/lssb
