On Fri, May 23, 2008 at 5:31 PM, Guy Boisvert boisvert.guy@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.