I did that but it looks the same. I did get an error even though it says write-caching is on. [root at dslg1 ~]# hdparm -W1 /dev/sda /dev/sda: setting drive write-caching to 1 (on) HDIO_DRIVE_CMD(setcache) failed: Invalid argument [root at dslg1 ~]# hdparm /dev/sda /dev/sda: readonly = 0 (off) readahead = 256 (on) geometry = 36472/255/63, sectors = 585937500, start = 0 [root at dslg1 ~]# [A [root at dslg1 ~]# dd if=/dev/zero of=/dev/sda bs=128k count=1k oflag=direct 1024+0 records in 1024+0 records out 134217728 bytes (134 MB) copied, 8.10005 seconds, 16.6 MB/s On Wed, Apr 20, 2011 at 5:45 PM, Joe Landman <landman at scalableinformatics.com> wrote: > On 04/20/2011 07:28 PM, Mohit Anchlia wrote: >> >> dd of=/dev/null if=/dev/sda bs=128k count=80k iflag=direct >> 81920+0 records in >> 81920+0 records out >> 10737418240 bytes (11 GB) copied, 83.8293 seconds, 128 MB/s > > Ok, this is closer to what I was expecting (really ~150 MB/s would make more > sense to me, but I can live with 128 MB/s). > > The write speed is definitely problematic. ?I am wondering if write cache is > off, and other features are turned off in strange ways. > > This is a 2 year old SATA disk > > [root at smash ~]# dd if=/dev/zero of=/dev/sda2 bs=128k oflag=direct > dd: writing `/dev/sda2': No space left on device > 16379+0 records in > 16378+0 records out > 2146798080 bytes (2.1 GB) copied, 20.8322 s, 103 MB/s > > Write cache is enabled. ?Turning write cache off (might not be so relevant > for a RAID0), > > [root at smash ~]# hdparm -W /dev/sda > > /dev/sda: > ?write-caching = ?1 (on) > [root at smash ~]# hdparm -W0 /dev/sda > > /dev/sda: > ?setting drive write-caching to 0 (off) > ?write-caching = ?0 (off) > > [root at smash ~]# dd if=/dev/zero of=/dev/sda2 bs=128k oflag=direct > dd: writing `/dev/sda2': No space left on device > 16379+0 records in > 16378+0 records out > 2146798080 bytes (2.1 GB) copied, 155.636 s, 13.8 MB/s > > See if you can do an > > ? ? ? ?hdparm -W1 /dev/sda > > and see if it has any impact on the write speed. ?If you are using a RAID0, > safety isn't so much on your mind anyway, so you can see if you can adjust > your cache settings. ?If this doesn't work, you might need to get to the > console and tell it to allow caching. > > > -- > Joseph Landman, Ph.D > Founder and CEO > Scalable Informatics, Inc. > email: landman at scalableinformatics.com > web ?: http://scalableinformatics.com > ? ? ? http://scalableinformatics.com/sicluster > phone: +1 734 786 8423 x121 > fax ?: +1 866 888 3112 > cell : +1 734 612 4615 >
