Sounds like you are well on your way. I am not too surprised on the time to completion. I probably underestimated/exaggerated a bit when I said after a few hours :) It took me over a day to grow one disk as well. But my experience was on a system with an older AMD 754 x64 Mother Board with a couple SATA on board and the rest on two PCI cards each with 4 SATA ports. So I have 8 SATA drives on my PCI (33Mhz x 4 bytes (32bits) = 133MB/s) bus of which is saturated basically after three drives. But this box sets in the basement and acts as my NAS. So for file access across the 100Mb/s network or wireless network, it does just fine. When I do hdparm -tT /dev/md1 I get read access speeds from 110MB/s - 130MB/s and for my individual drives at around 50 - 60 MB/s so the RAID6 outperforms (reads) any one drive and I am happy. Bonnie/Bonnie++ is probably a better tool for testing, but I was just looking for quick and dirty numbers. I have friends that have newer MB with half a dozen or almost a dozen SATA connectors and PCI-express SATA controller cards. Getting rid of the slow PCI bus limitation increases the speed by magnitudes... But this is another topic/thread... Congrats on your new kernel and progress! Cheers, Dan. ----- Original Message ----- From: Iain Rauch Sent: Tue, 6/5/2007 12:09pm To: Bill Davidsen ; Daniel Korstad ; Neil Brown ; linux-raid@xxxxxxxxxxxxxxx; Justin Piszcz Subject: Re: RAID 6 grow problem >>>>> raid6 reshape wasn't added until 2.6.21. Before that only raid5 was >>>>> supported. >>>>> You also need to ensure that CONFIG_MD_RAID5_RESHAPE=y. >>>>> >>>> I don't see that in the config. Should I add it? Then reboot? >>>> Don't know how I missed it first time, but that is in my config. >>> You reported that you were running a 2.6.20 kernel, which doesn't >>> support raid6 reshape. >>> You need to compile a 2.6.21 kernel (or >>> apt-get install linux-image-2.6.21-1-amd64 >>> or whatever) and ensure that CONFIG_MD_RAID5_RESHAPE=y is in the >>> .config before compiling. >>> >> >> There only seems to be version 2.6.20 does this matter a lot? Also how do I >> specify what is in the config when using apt-get install? >> > > 2.6.20 doesn't support the feature you want, only you can tell if that > matters a lot. You don't, either get a raw kernel source and configure, > or run what the vendor provides for config. Sorry, those are the option. I have finally managed to compile a new kernel (2.6.21) and boot it. >>>> I used apt-get install mdadm to first install it, which gave me 2.5.x then >>>> I >>>> downloaded the new source and typed make then make install. Now mdadm -V >>>> shows "mdadm - v2.6.2 - 21st May 2007". >>>> Is there anyway to check it is installed correctly? >>> >>> The "mdadm -V" check is sufficient. >> >> Are you sure because at first I just did the make/make install and mdadm -V >> did tell me v2.6.2 but I don't believe it was installed properly because it >> didn't recognise my array nor did it make a config file, and cat >> /proc/mdstat said no file/directory?? > mdadm doesn't control the /proc/mdstat file, it's written by the kernel. > The kernel had no active array to mention in the mdstat file. I see, thanks. I think it is working OK. I am currently growing a 4 disk array to an 8 disk array as a test, and if it that works I'll use those 8 and add them to my original 8 to make a 16 disk array. This will be a while yet as this first grow is going to take 2000 minutes. It looks like it's going to work fine, but I'll report back in a couple of days. Thank you so much for your help; Dan, Bill, Neil, Justin and everyone else. The last thing I would like to know is if it is possible to 'clean' the super blocks to make sure they are all OK. TIA. Iain - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
