On Fri, May 23, 2008 at 5:31 PM, Guy Boisvert <boisvert.guy at videotron.ca> wrote: > Well, i respect Open Source (and your opinion) very much but your comparison > imply that you had access to Adaptec's code! Maybe you really had access, i > don't know. If it's the case, then thanks you for having shared this > knowledge. No need to see adaptec source code. Actively developed and widely used open-source projects have great success over their closed-sourced big-budgeted projects. But you are correct at one point: I do not have right to blame any vendor without a fair comparison. However, none of them tends to show theirs for a comparison. But again, according to general inclination, I have a great feeling that I am right. Besides, this is all about the philosophy of open-source. linux kernel-raid still has my vote. Nevertheless, closed-source firmwares are everywhere, should we become paranoid? Maybe one day, but today, software linux kernel-raid is a good competitor in raid world, so I think it is a good choice to be paranoid about raid-stuff. (And of course we should, it is a cheap and great redundancy and for both data safety and service continuety) As an example, IBM's SAN devices are great I think. I'd used one and loved its performance and simplicity and elasticity. No software open-source solution can easily race with it. > You're talking about failed disks or controller? > > With controller, easy with my backups (or backup card). People with no > tolerance to failing controller arrange things accordingly like i do. > > With disks, irrelevant. This is what I'm trying to explain. Even the same vendor breaks compatibility between different vendors and I'm still talking about controller cards. I have to have backup cards for all configurations I have. After using a backup card, I either have to supply a new backup for controller card or have to transfer my configuration to a new card. For external solutions, I had only managed one configuration since now so no comment/comparison on them. > Well, educate me (and maybe others) M8. I learn things everyday and i like > it. How would you do RAID10 with 3 disks? I know how to do it with at > least 4, then 6 and so on. > > As for RAID-10, more below. Do not ask me, ask linux kernel raid10 developer [2] > Well, english is neither my native language! As for reading, i'm not that > bad but i may have misunderstood what you really meant. In that case, > please forgive me! I didn't meant to be rude or anything. Please accept my apologies. I think I behaved somehow rude. No need to talk about such non-technical issued in this kind of a list :) > I agree that the compatibility is great with software RAID. However, there > are some limitations at least in performance (Bus saturation, etc). > > I "tried to read" your reference (the URL you kindly provided me, thanks) > and, quote: > > "When the top array is a RAID 0 (such as in RAID 10 and RAID 50) most > vendors omit the "+", though RAID 5+0 is clearer." > > "RAID 1+0: mirrored sets in a striped set (minimum four disks; even number > of disks) provides fault tolerance and improved performance but increases > complexity. The key difference from RAID 0+1 is that RAID 1+0 creates a > striped set from a series of mirrored drives. In a failed disk situation > RAID 1+0 performs better because all the remaining disks continue to be > used. The array can sustain multiple drive losses so long as no mirror loses > both its drives." > > > So they say, and correct me if i'm wrong, that RAID10 is a RAID 1 of RAID 0. > A mirror of stripe sets. You said it's not that, i lost you on this one. linux kernel raid10 is a combination of both raid0 and raid1, not sum of them. As developer himself says in [2] So you have 3x500GB disks and 750GB raid-volume. [2] http://neil.brown.name/blog/20040827225440 Have a nice sunday.... P.S.: Once more, I am sorry to steal someone's thread which is about raid5/raid50 but I am currently using raid10 in many configurations and even after some disk failures I recovered easily. So, I can honestly recommend raid10 over raid5(0) configurations.