Yes, this is on of those "do my job for me" questions, have some pity:)
I'm at the limit for what I can do with the number of hard drives in a server without spending a substantial amount of money. I have four drives left to configure, and I can either set them up as a RAID 5 and dedicate a hot spare, or a RAID 10 with no hot spare. The size of each will be the same, and the RAID 5 will offer enough performance.
I'm RAID 5 shy, but I also don't like the idea of running without a hot spare. I'm not so interested in degraded performance, but the amount of time the system is without adequate redundancy. The server and drives are under a 13×5 4 hour response contract (although I happen to know that the nearest service provider is at least 2-3 hours away by car in the winter).
I should note that the server also has two RAID 1 arrays which would also be protected by the hot spare. Why don't they make drive cages with 9 bays! Heh.
Best Answer
What is the downtime tolerance of the array? Is it physically close, or in a remote data center? Bascially, if you can tolerate it, a cold spare allows you to do RAID10. The spare is sitting close by, but you have to physically do the swap. If that is not an acceptable scenario, then RAID5 with a hot spare is the only answer left.
Since you already have two RAID1 sets that have 1 drive failure tolerance, you really gain nothing by going RAID10 with no hot spare. Your entire array can still only survive a single drive failure.