(cc's added) On Wed, 19 Nov 2008 13:16:56 +0100 Michael Fuckner <michael@xxxxxxxxxxx> wrote: > Hi, > > I am using an Areca 1680-SAS-Controller with 16 SAS-HDD (Seagate 1TB > ST31000640SS). I set up a Raid6 with all 16 disks and formatted it with > XFS. The Controller has 512MB RAM and a BBU. The OS is installed to > another disk attached to the onboard AHCI controller. > > After doing some IO, the areca raidset is slower compared to the rate > directly > after boot. > > > [root@storage ~]# dd if=/dev/sdb1 of=/dev/null bs=1M count=50k iflag=direct > 51200+0 records in > 51200+0 records out > 53687091200 bytes (54 GB) copied, 59.6494 seconds, 900 MB/s > [root@storage ~]# mount /dev/sdb1 /data > [root@storage ~]# cd /data/ > [root@storage data]# ./iozone -i 0 -i 1 -s 32g -r 16m -S 6144 -t 8 -+r > -o >raid6_sync_t8.log > [root@storage data]# cd > [root@storage ~]# umount /data/ > [root@storage ~]# dd if=/dev/sdb1 of=/dev/null bs=1M count=50k iflag=direct > 51200+0 records in > 51200+0 records out > 53687091200 bytes (54 GB) copied, 76.4036 seconds, 703 MB/s > > I tested different Versions of Linux (Centos 5.2, OpenSUSE 11, Debian > Lenny) and Vanilla kernels 2.6.22-2.6.27, all show this behaviour. > > Idea why the device slows down after IO- or better: how to keep the high > rate? Is this reproducible foer Areca SATA Controllers (Type 11XX and 12XX) > > Regards, > Michael! -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
