Well, it's all done now. Thank you all so much for your help. There was no problem re-syncing from 8 to 16 drives, only that it took 4500 minutes.
Anyway, here's a pic of the finished product. http://iain.rauch.co.uk/images/BigNAS.png Speeds seem a little slower than before, no idea why. The only things I changed was to put 4 drives instead of 2 on each SATA controller, and change to XFS instead of ext3. Chunk size is still the same at 128K. I seem to be getting around 22MB/s write whereas before it was nearer 30MB/s. This is just transferring from a 1TB LaCie disk (2x500GB RAID0) so I don't have any scientific evidence of comparisons. I also tried hdparm -tT and it showed almost 80MB/s for an individual drive and 113MB/s for md0. The last things I want to know is am I right in thinking the maximum file system size I can expand to is 16TB? And also, is it possible to shrink the size of an array, if I wanted to build the disks into another array to change file system or another reason? Lastly, would I take a performance hit if I added USB/FireWire drives into the array - would I be better off building another NAS and stick with SATA (I'm talking good year off here hopefully the space will last that long). TIA Iain > 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@vger.kernel.org; > 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 [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
