The RAID array is at 80% on the resync, and approximately 25% of the data has been transferred from the backups. I believe the restore is running so slowly because of an error I made building the LVM on the backup system. Rather than 4 days to recover, it looks like it's going to take 16 days, or more. As you might imagine, I'm pretty nervous, as the backup is not fault tolerant, and the odds against the failure of a hard drive in a 16 day period are not astronomical by any means. This experience has prompted me to re-think my position on the backup system. My thoughts previously were I could save on money and effort by simply employing a JBOD volume managed by LVM for the backup system. After this experience, and even with the fact once the data is all transferred I can fix the backup system to allow proper performance (i.e. 50+ MBps, rather than the current average of about 4 MBps), I believe I will implement a RAID 5 array on the backup system. Still being limited by budgetary concerns, however, I saw something here which started me thinking again. I'm soon going to have a number of 1T drives available for use, and replacing the backup system's 1.5T drives with brand new 2T or 3T drives is going to be a daunting task. Is it possible, then to use the 1T drives combined with a like number of 1.5T to create a number (say, 6 or so) of 2.5T LVM volumes and then use mdadm to create a RAID 5 array assembled from the virtual volumes? Of course, I obviously could create a RAID 50 array from the individual discs, but them the member size would be limited to 1T, wasting .5T of each 1.5T drive. The difference in cost between a single 1.5T drive and five or six 3T drives is going to be pretty significant, and using the 1T drives as an interim step hopefully might allow me to put off buying the 3T drives until they have come down in price. I can easily assemble twelve TB from spare parts, which should last me well into the 3rd quarter of next year or beyond. Any comments? I know with 12 drives vs. 6 drives the liklihood of a failure is much greater, but the RAID 5 umbrella helps, and the fact this is a backup system means my required span of reliability is much lower than for the main system. -- 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
