Greetings ... Thanks for the quick reply ... 2009/3/11 Bruno Wolff III <bruno@xxxxxxxx>: > On Wed, Mar 11, 2009 at 09:52:45 +0200, > Clinton Lee Taylor <clintonlee.taylor@xxxxxxxxx> wrote: >> >> Was thinking or hoping, that we could do installs with a degraded >> RAID mirror ( single drive ), but I think I saw Jeremy ( could be >> wrong ), explain that we could rather reserver extra superblocks, and >> convert an ext3 partition to a RAID mirror, with a little less effort. > > Note that degraded and a raid 1 array that is complete but only has > one device are different cases. Okay, was really only referring to degraded raid 1 MD which would require another device ( partition ) to be complete. > Reserving extra space for the meta data is tricky, as different amounts > can be used (in different locations) depending how raid is being set up. > If you don't know how it will eventually be set up, you'll want to make > a worst cases guess. I will admit, I have not studied the on-disk format of ext2/3/4 or RAID1, the last time I did this, was in the good old days of DOS and FAT12/16 ... We really looking for only one case, RAID1, I don't see a need for anything else, in this topic's reguard ... Does RAID1 require twice as many superblocks as a standard ext3 partition? That is if we are talking about making a dirty conversion problem ... Part of this comes from M$ world, where a server can be installed with one disk and upgraded to second disk later, and bound into a mirror ... Would be great, if we could come up with a similar system, that is not all hackish ... Found a nice howto on booting using rescue disk and then creating degraded arrary to move running system onto and then rebooting into OS to added second drive into to mirror ... This might not yet be the right time to wish away my life ( no flame war or anything ), but if we added the extra superblocks into the filesystem and populated with the correct data, changed the partition ID to fd (Linux raid auto), maybe generate and updated initrd and reboot said server with extra hard drive in ... And presto, new degraded RAID1 setup ready to hot-add new spare md devices ... Yum jokes aside, this would a dream world for me, but I'm hoping that we could work towards that ... >> So, my question is, where could I find the information to mess with >> ext3 to RAID 1 conversion and could we really look at putting this >> into anaconda for installs. > > You need to change the partition code and run mdadm to create the array. This I would think would be to create a GUI interface ... Thinking maybe just messing with the KickStart system first and then grow out to include GUI/TUI options ... mdadm is already used to create the md devices, so if we add an extra option, to create a degraded raid1 partition, then I believe that part of my problem would be solve ... > As long as the meta data doesn't overwrite the data it should work. I'm not sure what you referring to know ... This comment seems out of place, but I could just be missing understanding what you getting at ... > If the intention is to support only raid 1 (the most common case where > people might want this), then I suggest creating the raid array first > with just one element. I think you are agreeing with me, or at least as I see it with my limit knowledge ... >> Motivation - Well, we believe in having our boot and OS ( lightly >> used ) drives always mirror to keep low, down time, but when we do >> upgrades or re-installs, we try and keep one drive out of the install >> to recover conf files, setting and the like and once the install is >> running ( a day or two ), we then add the drive back into the RAID and >> sync. At the moment, we have to take a spare drive with to do >> installs and upgrade and then hardware get's a little out of sync with >> what might have been originally purchased, leaving us with odd sized >> drives ... > > If you can throw in spare drives, you can use a drive at least as big > as what's in there, add it to the mirror, let it sync and remove it > from the mirror. And then you have your backup on disk. Well, this is how we are going it at the moment, but an upgrade the costs us an extra drive and mirroring twice per upgrade, which is what I'm trying to get around ... Backup of already installed system has a very limited use at the moment, but can be used as a selling point to the point hair people ... > I typically want to be able to do this when changing the disk layout. > I don't have spare disks to plug in and don't want to do a full recovery > from DVDs or tape, when using one of my mirrors is faster. Again, it sounds like you understand my pain ... Maybe this is really two ideas and that we should only be disuccing ananconda here, but I'm sure Jeremy said that he had done the reserver the needed superblocks to do a conversion and would be a worthwhile trade off, if this was a working idea ... If anybody thinks this is off topic, then I will try and chat with Niel Brown, seeing that I believe that he might be able to help, but I would rather be seeing this in Fedora, seeing that I am Fedora user and could help, even a little ... Thanks Mailed LeeT _______________________________________________ Anaconda-devel-list mailing list Anaconda-devel-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/anaconda-devel-list
