Cory Coager put forth on 1/14/2011 2:48 PM: > On 01/14/2011 02:51 PM, Stan Hoeppner wrote: >> Make sure the write cache on the P600 (what size is it BTW?) is enabled and that >> the BBU is in working order. Also make sure the P600 is disabling the write >> caches on the drives themselves. Then... >> > Write cache is enabled on the controller, the size is 512MB, BBU is in good > conditioned (checked with the HP utility). How do I check the write cache on > the drives? The controller should do this automatically. You'll have to check the docs to verify. This is to safeguard data. The BBWC protects unwritten data in the controller cache only, not the drives' caches. It won't negatively affect performance if the drives' caches are enabled. On the contrary, it would probably increase performance a bit. It's simply less safe having them enabled in the event of a crash. After rereading your original post I don't think there's any issue here anyway. You stated you have 24 drives in 2 arrays (although you didn't state if all the disks are on one P600 or two). >> Mount with 'nobarrier' so XFS isn't interfering with the hardware cache >> performance of the P600. With barriers enabled (the default) XFS will >> periodically flush the cache on the RAID card causing write performance problems. >> > Already using nobarrier. This was the important part I was looking for. It's apparently not a cache issue then, unless the utility is lying or querying the wrong controller or something. Nothing relevant in dmesg or any other logs? No errors of any kind? Does iostat reveal anything even slightly odd? I also just noticed you're testing writes with a 1k block size. That seems awefully small. Does the write throughput increase any when you test with a 4k/8k/16k block size? BTW, this is an old machine. PCI-X is dead. Did this slow write trouble just start recently? What has changed since it previously worked fine? You're making it very difficult to assist you by not providing basic troubleshooting information. I.e. What has changed since the system functioned properly? When did it change? Did it ever work properly? Etc. God I hate pulling teeth... :) -- Stan _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
