> At 9:06 pm +0100 24/1/01, Aley Keprt wrote: > >> > How can it increate a probility of a disk crash? Is it just because of > >using > >> > two disks? > >> > Is so, it is a nonsense. > >> > >> No. Disks come with a MTBF. If you add disks, this MTBF remains > >> (almost) constant. The MTBF of the entire raid will then decrase > >> when the number of disks increase. > > > >I wrote this already, so just for completeness: > >Higher data loss probability is caused by usage of two disks. It has nothing > >to do with RAID. > >If you use two disks without RAID0, you have the same data loss probability. > > Wrong. With RAID0, you lose the integrity of your *entire* filesystem when > _either_ of the disks crash. So you expect to potentially lose 100% of your > data every (MTBF/2) years.
Of course. But this is software problem "How many data you lose when your disk crashes." We talked about hardware problems. > Wheras with independent disks, you only lose half your data when one disk > crashes. If you say that both disks are expected to crash after MTBF years, > then that's already a 2x improvement over RAID0. Usually you only lose one sector or some clusters. If you surprisingly lose whole disk, it can be usually repaired, since data are ok, and there are problems with electronics etc. > >Have you ever heard about backuping? I practise this for years, and it > >helped me much! > > Yes, we do this a lot at work. But I daresay that restoring a few terabytes > of data would be pretty tedious if we ever needed to do it. Regardles of how many bytes you want to keep up, you should backup. At least I still think. > > Andrew Aley
