On Tue, July 28, 2009 11:09 am, Tirumala Reddy Marri wrote: > While raid-6 is building I noticed writes are going on to all the > drivers. Whereas in raid-5 I see writes happening to only one drive. > Any clue ? Because raid5 != raid6...... For raid5, mdadm creates a degraded array and recovers to a spare. So it only writes to the spare. For raid6, mdadm doesn't try to be so clever (the tradeoffs are difference) and just creates a non-clean array so all the P and Q blocks get written. NeilBrown > > ---------- iostat dump for raid-6 --- > Device: tps MB_read/s MB_wrtn/s MB_read MB_wrtn > sda 152.76 23.81 3.74 47 7 > sdb 181.91 25.35 5.50 50 10 > sdc 161.31 24.84 3.30 49 6 > sdd 153.77 23.52 4.02 46 8 > sde 169.85 26.29 3.27 52 6 > sdf 0.00 0.00 0.00 0 0 > sdg 0.00 0.00 0.00 0 0 > sdh 0.00 0.00 0.00 0 0 > sdi 0.00 0.00 0.00 0 0 > > Device: tps MB_read/s MB_wrtn/s MB_read MB_wrtn > sda 152.02 24.05 3.44 47 6 > sdb 168.18 26.23 4.14 51 8 > sdc 163.64 22.76 3.69 45 7 > sdd 166.67 24.37 4.04 48 8 > sde 166.16 24.78 3.57 49 7 > sdf 0.00 0.00 0.00 0 0 > sdg 0.00 0.00 0.00 0 0 > sdh 0.00 0.00 0.00 0 0 > sdi 0.00 0.00 0.00 0 0 > --------------- > Thanks, > Marri > -- > 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 > -- 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
