Load and CPU usage are 2 different things, but somehow related. What is the CPU load during this time? >From what I have seen, the RAID software md, whatever, uses almost no CPU. So, I don't think it is a CPU issue. Even with RAID5, the CPU load is very low. Even during a rebuild! Use top to see cpu usage. Use sar (man sar) for keeping a log of cpu load and a lot of other stuff. "sar -d" to see disk usage. Maybe you are swapping, this would be bad. Add RAM if so. I bet your 2 disks are the bottle neck. If the RAID1 can be tuned, I don't know how. But the first step is to determine what the bottle neck is. -----Original Message----- From: linux-raid-owner@vger.kernel.org [mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Matthew Simpson Sent: Monday, February 02, 2004 6:18 PM To: linux-raid@vger.kernel.org Subject: how to turn down cpu usage of raid ? Help! I am having complaints from users about CPU spikes when writing to my RAID 1 array. Is there a way I can tune software RAID so that writing updates doesn't interfere with other applications? [can I nice the raid1d process?] Specifically I experience giant slowdowns in a hosted application whenever someone unpacks a tar file or the like. Load averages are 1.10 - 2.00 during writes, but 0.00 to 0.05 otherwise. root@ns2:~# cat /proc/mdstat Personalities : [linear] [raid0] [raid1] [raid5] read_ahead 1024 sectors md0 : active raid1 hdc1[1] hda1[0] 78979200 blocks [2/2] [UU] unused devices: <none> root@ns2:~# cat /etc/raidtab raiddev /dev/md0 raid-level 1 nr-raid-disks 2 nr-spare-disks 0 chunk-size 4 persistent-superblock 1 device /dev/hda1 raid-disk 0 device /dev/hdc1 raid-disk 1 This is a pentium IV 2.5GHz system with 1GB of RAM. IDE interface: PCI device 8086:24cb (Intel Corp.) (rev 1). -- 82820 Camino 2 chipset - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
