Thanks for the replies. I began using mdadm in ubuntu 8.04, which I believe was the 2.6.24 kernel. The rebuild times under this kernel with 6 500GiB drives were very fast... I think like 100-200m, but that was with a raid5. Using raid6 under ubuntu 9.04 , which was 2.6.28 I would get 20m rebuild times on raid6 with 1TiB drives. This would take literally 10-14 hours depending on my array size. Now with ubuntu 9.10, which is 2.6.31 I get like 50-75m on the same exact raid6 rebuild. I didn't realize that software/OS mattered so much for performance from kernel to kernel. I need to look more into this bitmap that people have mentioned. Beolach wrote: > On Wed, Nov 4, 2009 at 11:03, Andrew Dunn <andrew.g.dunn@xxxxxxxxx> wrote: > >> I sent this a couple days ago, wondering if it fell through the cracks or if I am asking the wrong questions. >> >> ------ >> >> I will preface this by saying I only need about 100MB/s out of my array >> because I access it via a gigabit crossover cable. >> >> I am backing up all of my information right now (~4TB) with the >> intention of re-creating this array with a larger chunk size and >> possibly tweaking the file system a little bit. >> >> My original array was a raid6 of 9 WD caviar black drives, the chunk >> size was 64k. I use USAS-AOC-L8i controllers to address all of my drives >> and the TLER setting on the drives is enabled for 7 seconds. >> >> > <snip mdadm -D> > > That array should easily be able to fill your 100MB/s speed requirement. If > you really are only accessing over a 1Gib/s link, I wouldn't worry much > about tweaking for performance. > > >> I have noticed slow rebuilding time when I first created the array and >> intermittent lockups while writing large data sets. >> >> Per some reading I was thinking of adjusting my chunk size to 1024k, and >> trying to figure out the weird stuff required when creating a file system. >> >> > > Can you quantify "slow rebuilding time"? And was that just when you first > created the array, or do you still see slowness when you check/repair the > array? Using a write-intent bitmap might help here. > > I don't know that any of the options discussed so far are likely to help w/ > intermittent lockups. When you see them, are you writing your data over > the network? How badly does it lock up your system? What kernel version > are you using? > > > Good Luck, > -- > Conway S. Smith > -- Andrew Dunn http://agdunn.net -- 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
