On Wed, Jun 06, 2007 at 02:30:24PM +0300, Pasi Kärkkäinen wrote: > Hi! > > When anaconda initializes a disk and creates a new partition (the default partition layout), > the first partition is set to start from the sector 63. > > In normal cases and with normal harddisks this is fine. > > But if your disk is a SAN LUN (iSCSI, FC), this could cause all the IO to be > "misaligned", causing a performance drop. Many SAN arrays want the partitions > to be aligned on a 8 kB boundary, or some even on 64 kB boundary. > > Would it cause problems if anaconda automatically aligns partitions to start > from a sector that is a multiple of 8 (or even 64 kB) ? Or maybe add an option > to specify how to align the partitions? > > VMware document about aligning partitions for ESX/VMFS for optimal > performance: > > http://www.vmware.com/pdf/esx3_partition_align.pdf > And more about the performance gains when aligning partitions (from the pdf above): Throughput Increase Min = 2% Max = 62% Avg = 12% Latency Decrease Min = 7% Max = 33% Avg = 10% Results of course depend of the SAN array used, and also on other factors. Btw. this partition alignment should also be done in virtual machine (domU) virtual disks. -- Pasi -- fedora-devel-list mailing list fedora-devel-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/fedora-devel-list
