Hi there, I've got a question about creating a RAID-1 array on a remote server - ie: if the operation fails, it's going to be very expensive. The server has two 200 GB drives and during a hurried re-install of CentOS 5.2 the creation of software RAID partitions was omitted. This means that the array would include the currently active partition on which the kernel is installed. So my first question is as to the feasibility of this operation, and its safety: any comments? The following may give an insight into the current setup should you need it to answer my question more accurately. ------------------------------------------------------------- # fdisk -l Disk /dev/sda: 203.9 GB, 203928109056 bytes 255 heads, 63 sectors/track, 24792 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sda1 * 1 13 104391 83 Linux /dev/sda2 14 24773 198884700 8e Linux LVM Disk /dev/sdb: 203.9 GB, 203928109056 bytes 255 heads, 63 sectors/track, 24792 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sdb1 * 1 13 104391 83 Linux /dev/sdb2 14 24773 198884700 8e Linux LVM ------------------------------------------------------------- # mount /dev/mapper/VolGroup00-LogVol00 on / type ext3 (rw) proc on /proc type proc (rw) sysfs on /sys type sysfs (rw) devpts on /dev/pts type devpts (rw,gid=5,mode=620) /dev/sda1 on /boot type ext3 (rw) tmpfs on /dev/shm type tmpfs (rw) none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw) sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw) ------------------------------------------------------------- # pvdisplay Found duplicate PV g7ZWtzNQcHx2PMQghP0NBHDXuYcaYqAt: using /dev/sdb2 not /dev/sda2 --- Physical volume --- PV Name /dev/sdb2 VG Name VolGroup00 PV Size 189.67 GB / not usable 15.34 MB Allocatable yes (but full) PE Size (KByte) 32768 Total PE 6069 Free PE 0 Allocated PE 6069 PV UUID g7ZWtz-NQcH-x2PM-QghP-0NBH-DXuY-caYqAt ------------------------------------------------------------- # lvdisplay Found duplicate PV g7ZWtzNQcHx2PMQghP0NBHDXuYcaYqAt: using /dev/sdb2 not /dev/sda2 --- Logical volume --- LV Name /dev/VolGroup00/LogVol00 VG Name VolGroup00 LV UUID rvPZJS-6Z7a-kXzk-aLcM-vv13-eRCK-kjg6I1 LV Write Access read/write LV Status available # open 1 LV Size 187.72 GB Current LE 6007 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:0 --- Logical volume --- LV Name /dev/VolGroup00/LogVol01 VG Name VolGroup00 LV UUID zvxDsa-MZXn-akSA-DlzC-49IX-65Fo-HPBuyJ LV Write Access read/write LV Status available # open 1 LV Size 1.94 GB Current LE 62 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:1 ------------------------------------------------------------- Judging from the "Found duplicate " messages produced by pvdisplay and lvdisplay, as well as the mount output, it seems that the root partition is being loaded from /dev/sdb2. What /dev/sda2 is doing right now is, I guess, completely sweet FA. Can anyone point me to the way of finding out a file's physical location on disc so that I can verify this is the case? So, for example, I would like to check that my latest edit to ~/somefile.txt is in fact on /dev/sdb1 at location xyz and that can be verified by using dd to copy those bytes to a file in /tmp. Having started reading the docs related to creating a RAID device, it seems likely that the order of the listed devices is significant when the array is initialised. However, I haven't yet been able to confirm that were I to write mdadm -C /dev/md0 --level raid1 --raid-disks 2 /dev/sdb1 /dev/sda1 that it would start to copy data from sdb1 to sda1 - or have I misunderstood the initialisation process? These questions may not seem very well framed, but some initial guidance while I'm still reading into the problem would be appreciated. Best wishes Michael -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
