On 04/20/2011 07:50 PM, Mohit Anchlia wrote: > 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 You might need sdparm sdparm -a /dev/sda | grep WCE With WCE on I see [root at smash ~]# sdparm -a /dev/sda | grep WCE WCE 1 and with it off, I see [root at smash ~]# hdparm -W0 /dev/sda /dev/sda: setting drive write-caching to 0 (off) write-caching = 0 (off) [root at smash ~]# sdparm -a /dev/sda | grep WCE WCE 0 You might need to change WCE using sdparm --set=WCE -a /dev/sda or similar ... > > /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 >> -- 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
