Hi, My Colleagues and I are working on constructing a large low cost data archive. One option is that we construct disk arrays from linux servers each containing 8 160GB IDE drives. The 8 drives will be organized into a single softweare RAID5 array. I have 2 prototype systems that seem to work well. Once the arrays are filled, the data should never change. I can mount the disks read-only easily enough, but the md software doesn't care about that. I've found that if power is removed from my software RAID systems, or they crash with a kernel panic, upon reboot the raid5d sync is woken up, and the the disk arrays re-syncs for a few hours. It is not clear to me why this is the case. A more troubling error condition arises when one of the disks does not come up at boot time because of a power or cabling problem, for example. If this happens, the remainder of the array will start up with 7/8 disks and mark the 8th disk as bad in the super block of each of the good disks. Fixing the cable and rebooting the array still leaves the system compromised. I want a system that behaves like a RAID array constructed from CD-ROMS. The RAID software should have the knowledge that the data on the disks will never be altered, and should never be altered. There seems to be no "read-only" option for the raidtab. mdadm has a -o option that marks an array as read-only. This will prevent the array from needing to be re-synced after a hard crash, but I can't mark the array as read-only until it has been assembled, leaving the array vulnerable to the cabling problem described above. That is, mdadm -A will not work with the -o option. I am considering making the hard disk devices (ie. /dev/hd*) read-only, but I am not sure that linux software RAID will work if I do. Will it work? Does anyone have advice on how to make my static data remain static? Thanks -Andy ------------------------------------------------------------------------- Andrew Smith (301) 405-2152 Department of Physics asmith@umdgrb.umd.edu University of Maryland College Park, MD 20742-4111 ------------------------------------------------------------------------- - 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
