Does test 1 have 4 processes? Does test 2 have 1 process? The number of testing processes should be the same in both tests. } -----Original Message----- } From: linux-raid-owner@xxxxxxxxxxxxxxx [mailto:linux-raid- } owner@xxxxxxxxxxxxxxx] On Behalf Of Raz Ben-Jehuda(caro) } Sent: Monday, March 06, 2006 6:46 AM } To: Linux RAID Mailing List } Cc: Neil Brown } Subject: raid5 performance question } } Neil Hello . } I have a performance question. } } I am using raid5 stripe size 1024K over 4 disks. } I am benchmarking it with an asynchronous tester. } This tester submits 100 IOs of size of 1024 K --> as the stripe size. } It reads raw io from the device, no file system is involved. } } I am making the following comparsion: } } 1. Reading 4 disks at the same time using 1 MB buffer in random manner. } 2. Reading 1 raid5 device using 1MB buffer in random manner. } } I am getting terrible results in scenario 2. if scenario 1 gives 120 MB/s } from } 4 disks, the raid5 device gives 35 MB/s . } it is like i am reading a single disk , but by looking at iostat i can } see that all } disks are active but with low throughput. } } Any idea ? } } Thank you. } -- } Raz } - } 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
