On Thu, 23 Apr 2009 13:16:28 +0300, "Pasi Kärkkäinen" <pasik@xxxxxx> wrote: >> > Yes, I have (by the way, do you know how long ext3 takes to create a >> > 6TB filesystem???). >> >> It depends on what you consider to be "long". The last box I built had >> 8x 1TB 7200rpm disks in software md RAID6 = 6 TB usable, DAS, consumer >> grade motherboard, and 2 of the 8 ports were massively bottlenecked by >> a 32-bit 33MHz PCI SATA controller, but all 8 ports had NCQ. This took >> about 10-20 minutes (I haven't timed it exactly, about a cup of coffee >> long ;)) to mkfs ext3 when the parameters were properly set up. With >> default settings, it was taking around 10x longer, maybe even more. >> > > Interesting information.. what settings did you tweak for faster mkfs? Just > the things mentioned below? Yes, all of the ones mentioned. >> My findings are that the default settings and old wisdom often taken >> as axiomatically true are actually completely off the mark. >> >> Here is the line of reasoning that I have found to lead to best results. >> >> RAID block size of 64-256KB is way, way too big. It will kill >> the performance of small IOs without yielding a noticeable increase >> in performance for large IOs, and sometimes in fact hurting large >> IOs, too. >> >> To pick the optimum RAID block size, look at the disks. What is the >> multi-sector transfer size they can handle? I have not seen any disks >> to date that have this figure at anything other than 16, and >> 16sectors * 512 bytes/sector = 8KB. >> > > Hmm.. how can you determine multi-sector transfer size from a disk? hdparm -i /dev/[hs]d[a-z] Gordan -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
