On Oct 18, 2007, at 4:42 AM, Andreas Dilger wrote: > On Oct 17, 2007 15:35 -0400, Brock Palen wrote: >> We are doing some testing, >> >> For a OST with a xserve raid connected to linux, is it better to not >> have a partition table >> >> mkfs.lustre /dev/sda >> >> or to have a partition? >> fdisk /dev/sda >> mkfs.lustre /dev/sda1 > > For RAID 5/6 devices we recommend NOT having a partition table. > The reason > is that the partition table offsets the data partitions by a small > amount > (512 bytes usually) and this causes writes to span multiple RAID > chunks and > unnecessary read-modify-write activity. > > For best performance, pick a RAID chunk size that divides evenly into > 1MB (e.g. 4 or 8 data disks + parity). The ldiskfs mballoc code works > to align the allocation with the RAID chunk size for best performance.
Thanks I will keep this in mind. I did some basics test, 1MDS 1OST 1raid5 (half a xserve raid) Using tiobench on 1 client, using no partition table netted about 5MB/s faster for streaming read/write. I will scale up my tests though and try some other raid configurations. Thanks for the help. > > Cheers, Andreas > -- > Andreas Dilger > Principal Software Engineer > Cluster File Systems, Inc. > > > _______________________________________________ Lustre-discuss mailing list [email protected] https://mail.clusterfs.com/mailman/listinfo/lustre-discuss
