On Friday July 25, david.anderson@calixo.net wrote: > Hi all, > > First of all I would like to thank the developers of the linux software > RAID system for their excellent work which has saved my data on several > occasions. > > Recently I lost one of the disks on my software RAID5 (3x2Gb SCSI on a > 2.4.21 Debian Woody). Seeking replacements, I came across two 4Gb SCSI > drives. After inserting one of them as a temporary replacement for the > dead 2Gb, I am now looking into ways of better integrating these two new > disks into my existing setup. > > The most best solution I came up with was to extend the array's overall > capacity from 4 to 8Gb. To do this I would first combine the two > remaining 2Gb disks into a RAID0 array, and then combine that array and > the two 4Gb disks into a RAID5 array. To clarify this, here is a diagram > of this solution: http://polaris-outpost.net/vrac/Solution.png . > > However, there are a few things I would like to know before I make an > attempt at this setup. First of all, would the software-raid driver > handle disk failures properly even with the RAID within RAID? I do not > see why not, but I'd rather be sure before I jump... Yes. This definately works. Though it wouldn't hurt for you to simulate a failure just to convince yourself. > The other question I have is about performances. Would the RAID0 array > significantly impact on the overall I/O perfomances of the RAID5 array? > If anyone has already had the opportunity of comparing performances on a > regular RAID5 and a RAID5 containing a RAID0, I would be interested in > the results. I will of course conduct my own tests once this setup is in > place. I haven't tested it myself (though I have a setup rather like this running at the moment: used to 36Gig drives while waiting for a failed 72Gig drive to be replaced). NeilBrown > > Thanks in advance for your help > David Anderson > - > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
