the birdhouse in my soul

In the aftermath of the previous post, I ended up monitoring the progress of several huge pvmove and md RAID1 resync operations. Running "vmstat 1" however only shows pvmove block I/O activity, but not md RAID1 resyncing. Fortunately, "dstat -d" shows the reads and writes of both pvmove and md RAID1 resync. ("-d" is automatically included in "dstat -a" by the way.) N.B. This only affects block I/O measurements, you'll still see the impact on interrupts and CPU statistics in vmstat.

Most Linux system-administrators are well aware of the benefits of LVM. With online resizing of filesystems and migration of data from one disk to another, it's fantastic. But don't assume that your system will do everything for you. If your system has one disk, that you used as a physical volume (PV) in a volume group (VG), where your root partition is stored as a logical volume (LV), you can easily add a new disk. Add the disk physically, boot up, use pvcreate and vgextend to include the new disk in the existing volume group. Just don't reboot, at least, not yet ! Your system requires a manual rebuild of its initial ram disk /sbin/mkinitrd -f /boot/initrd-2.6.18-92.1.10.el5.img 2.6.18-92.1.10.el5 If you forget to do this, your system will not boot, because it won't find all the components necessary to activate the VG it needs to access the root filesystem. Symptoms: kernel loads, initrd loads, root filesystem can't be mounted because the volume group doesn't e...