Hi, I've a few questions in relation to mdadm and performance. System details follow below: Intel Atom 330 @ 1.6Ghz (dualcore, HT), 4GB RAM 05:00.0 SCSI storage controller: HighPoint Technologies, Inc. RocketRAID 230x 4 Port SATA-II Controller (rev 02) 00:0b.0 SATA controller: nVidia Corporation MCP79 AHCI Controller (rev b1) /dev/sda: Model=Corsair CSSD-F60GB2, FwRev=1.1, SerialNo=10326505580009990027 /dev/sdb: Model=WDC WD20EARS-00MVWB0, FwRev=51.0AB51, SerialNo=WD-WCAZA1022443 /dev/sdc: Model=WDC WD20EARS-00MVWB0, FwRev=50.0AB50, SerialNo=WD-WMAZ20152590 /dev/sdd: Model=WDC WD20EARS-00MVWB0, FwRev=50.0AB50, SerialNo=WD-WMAZ20188479 /dev/sde: Model=SAMSUNG HD204UI, FwRev=1AQ10001, SerialNo=S2HGJ1RZ800964 /dev/sdf: Model=WDC WD20EARS-00MVWB0, FwRev=51.0AB51, SerialNo=WD-WCAZA1000331 /dev/sdg: Model=SAMSUNG HD204UI, FwRev=1AQ10001, SerialNo=S2HGJ1RZ800850 mdadm -D /dev/md0: /dev/md0: Version : 1.2 Creation Time : Tue Oct 19 08:58:41 2010 Raid Level : raid5 Array Size : 5851054080 (5580.00 GiB 5991.48 GB) Used Dev Size : 1950351360 (1860.00 GiB 1997.16 GB) Raid Devices : 6 Total Devices : 6 Persistence : Superblock is persistent Update Time : Fri Oct 29 15:42:42 2010 State : active, recovering Active Devices : 6 Working Devices : 6 Failed Devices : 0 Spare Devices : 0 Layout : left-symmetric Chunk Size : 128K Reshape Status : 57% complete Delta Devices : 2, (4->6) Name : ion:0 (local to host ion) UUID : e6595c64:b3ae90b3:f01133ac:3f402d20 Events : 35293 Number Major Minor RaidDevice State 0 8 81 0 active sync /dev/sdf1 1 8 17 1 active sync /dev/sdb1 4 8 49 2 active sync /dev/sdd1 3 8 33 3 active sync /dev/sdc1 5 8 65 4 active sync /dev/sde1 6 8 97 5 active sync /dev/sdg1 Question 1: I saw that in Linux 2.6.36 (perhaps earlier versions as well) you have the kernel config option CONFIG_MULTICORE_RAID456. I tried enabling it, booted to 2.6.36 from 2.6.35, and rebuilding of the array continued where it left off before reboot. However, the performance was abysmal.. around 16MB/s compared to 70MB/s without the option turned on. Is this a bug, or is it because the Atom has no grunt to speak of? Question 2: The array is now recovering since I've grown it to 6 from 4 devices: $ cat /proc/mdstat Personalities : [raid6] [raid5] [raid4] md0 : active raid5 sdf1[0] sde1[5] sdg1[6] sdc1[3] sdd1[4] sdb1[1] 5851054080 blocks super 1.2 level 5, 128k chunk, algorithm 2 [6/6] [UUUUUU] [===========>.........] reshape = 57.7% (1126387328/1950351360) finish=718.0min speed=19125K/sec unused devices: <none> Is there a way to speed it up? /proc/sys/dev/raid/speed_limit_min is 100000 (100k), /proc/sys/dev/raid/speed_limit_max is 1000000 (1000k). Question 3: Before I created this RAID5 array I did a quick RAID0 test array just for fun, using 2 full devices (not partitions). Now I have this: mdadm --examine --verbose --scan ARRAY /dev/md/raid0-test level=raid0 metadata=1.2 num-devices=2 UUID=b84cc081:1ae27b49:d5ae466c:377ba300 name=ion:raid0-test devices=/dev/sdf,/dev/sdb ARRAY /dev/md/0 level=raid5 metadata=1.2 num-devices=6 UUID=e6595c64:b3ae90b3:f01133ac:3f402d20 name=ion:0 devices=/dev/sdg1,/dev/sdf1,/dev/sde1,/dev/sdd1,/dev/sdc1,/dev/sdb1 Is it safe to erase the raid0-test superblocks on device /dev/sdb and /dev/sdc or will it interfere with my RAID5 array (which is lying on top of partitions) ? Many thanks, // Mathias -- 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