On Wed, Aug 6, 2008 at 8:01 AM, Naresh Narang <[EMAIL PROTECTED]> wrote: > > --- On Thu, 7/24/08, Yashpal Nagar <[EMAIL PROTECTED]> wrote: > > >> What I also want to understand is, does hardware RAID >> system really >> care about data, what happens to the data if one, add a >> disk into the >> existing logical drive? >> e.g logicaldrive 2, what if I unkmark the disk as spare, >> what happens >> to logical drive/date?? >> > > > Once array has been created, you cannot remove disk.
True, But you can very well remove and add hot spare disks. You can also remove even a single hot spare drive in a RAID5 array. > Removing one disk from Raid 5 set will cause array to become degraded, > removing 2 disks will fail the virtual drive with loss of data. Correct. I experimented a bit on this and found expanding a array carefully does't lead to any data loss. Here is what experimented Created a RAID0 (called array B) with single disk(146GB) with hpacucli. Initialized the disk into LVM. created a VG and a LV under LVM2 and put some data on the logical volume. Now i went ahead and expanded the Array B with hpacucli, with another disk(146GB) into RAID0, it took 15min/per GB to expand the array as HP documentation states. After expanding finished, I saw both the disks were appearing OK into the array B. hpacucli slot=<0> array B add drives=<id> Now i needed to expand the logical drive hpacucli slot=<> ld 2 modify size=max #here I found logical drive expansion almost instant, however HP document states its should be 15GB/min Under Linux, after any logical drive expansion under RAID system, you must need to reboot the server. After reboot, run fdisk -l, I found the drive now expanded, showed me 293.6 GB instead of 146GB earlier, i needed to pvresize the physical volume into the LVM and VG was automagically expaned. Mounted the LV and found the data intact with no problem. So in theory it appears like expanding the array with new disks works, with no data loss and you require a reboot into Linux. My OS was RHEL 4.0 ES Cheers! Yash _______________________________________________ ilugd mailinglist -- [email protected] http://frodo.hserus.net/mailman/listinfo/ilugd Archives at: http://news.gmane.org/gmane.user-groups.linux.delhi http://www.mail-archive.com/[email protected]/
