Originally Posted by DotJun
Earlier in the thread, software raid was suggested to me. I've done some light reading on the subject and have some questions to those that implement this type of setup.
I'm only familiar with FlexRAID so can only comment on your questions in that context:"1) how many drive failures at one time needed to lose the array?"
In general, one more than you are protected for. FlexRAID allows for multiple parity drives to protect against simultaneous drive failures. Even in the case of failure exceeding your protection limit, you never lose the whole array, just the drives that fail. Each drive is an independent NTFS formatted drive that can be assigned a drive letter and accessed directly."3) I saw some documentation that stated software raid slows down as you add more drives. Is this true?"
FlexRAID has two independent components -- drive aggregation and RAID protection. Drive aggregation forms the array by combining multiple drives into a single volume that appears as a single drive letter. The RAID module does the actual protection of the drives by building the parity drive(s). These modules are independent. You don't need to aggregate drives into a single volume to have the RAID module protect them. You could have 10 disks with individual drive letters that are shared over the network as individual drives and use the RAID module to protect that collection. Since parity disk updating is a scheduled or on-demand task those shared drives will operate at their full speed without any hit in performance. If you use the drive aggregation module then you have inserted a layer of software in the drive access path. I don't have any info on the impact of drive aggregation on R/W performance."4) what happens to your data if you have a power outage during a write?"
I would imagine the same thing that would happen if you incurred a power outage when writing any disk. That data will be corrupted and possibly the whole disks partition table will get trashed. But the damage will be confined to the disk that was being written. Again, with FlexRAID you never lose the full array, just the disk with the problem because files are contained on a single disk and not striped."I looked at the "do parity later" thing and I think it falls outside my comfort zone since I use my server for more than just media storage."
Then don't use FlexRAID. FlexRAID is good for media storage because you write infrequently and read a lot. Adding media a couple times a week and scheduling a nightly parity update is quite acceptable and allows the drives to operate at full speed, unencumbered with the overhead of continuous RAID. For people that need/want continuous RAID, I only recommend a hardware RAID solution. As I mentioned in a post above, you can use both on the same server -- FlexRAID for your media serving array and a hardware RAID enclosure for your non-media data you consider critical -- MediaSonic is a good product and there are others to choose from.