On Monday 12 January 2004 11:02, Marc Bevand wrote: > Maarten v d Berg wrote: > > [...] > > Otherwise, adding a 40 GB physical volume to a 120 GB raid5 / LVM set > > just gives me one 120 GB partition and [room for] another 40 GB > > partition. There is NO gain whatsoever using LVM here compared to when I > > would just have added a single 40GB disk all by itself without using LVM > > in the first place, is there ? > > > > This has always left me wondering. Did I miss something (except using > > some alpha FS-resize code...) ? > > This is precisely the point, you have to resize your filesystem so that > the extra space added to your LVM device is used. There are many > options, you can either use a userland tool (resize2fs, resize_reiserfs, > ...) for resizing an *unmounted* filesystem, or you can do it in the > kernel (mount -o remount,resize=<size> <device>). As you can see, doing > it in the kernel has the extra advantage of allowing you to resize a > *mounted* filesystem. My raid filesystem is not part of the normal linux FS tree, so for me it is perfectly okay to umount the system. I tend to only use reiserfs. > Filesystem resizing is more stable than you think, for example the > commercial program Partition Magic is based on resize2fs (but I am not > sure if I can convince you with this example since proprietary software > is evil :P). I know partition magic but at the time I tried it it did not understand reiserfs so I dropped it. I don't know what the current version can do. In any case I didn't want to run the risk at the time; I had something which could be called a "backup" (with some imagination) but it consisted of several tapes, disks and whatnot that could help restoring in case of a disaster but it was by no means near anything complete nor recent. In other words, restoring would have cost me at least a full weekend and would have cost me anything between 5 - 20% of my data. I can accept that kind of risk for statistic 'normal' disasters but not for experiments with a higher- than-normal risk of losing the entire filesystem. The problem with adding a non-redundant drive to an existing raid-based LVM persists however. By adding that one drive and extending the FS to include that you introduce a single point of failure. Bye bye raid-redundancy... Greetings, Maarten - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
