Hi Joe, When you get chance can you please at my mail? It will be helpful to get your advise. On Wed, Apr 20, 2011 at 6:16 PM, Mohit Anchlia <mohitanchlia at gmail.com> wrote: > Yes indeed. As soon as I sent you last email I realized that and set > the write back option. Now I get 130MB/s better but still nowhere > close to 600MB/s as advertised or what others say one should see. > > What are your recommendations about HW choice? What is more > preferrable and better? > > Another question do I need to set WCE on all the disks first before > creating RAID0? Or can I do that after creating RAID0? I tried to set > WCE on existing RAID0 but it fails "change_mode_page: failed fetching > page: Caching (SBC)". > > ?sdparm --set=WCE --save /dev/sda > ? ?/dev/sda: FUJITSU ? MBD2300RC ? ? ? ? D809 > > dd if=/dev/zero of=/dev/sda bs=128k count=80k oflag=direct > 81920+0 records in > 81920+0 records out > 10737418240 bytes (11 GB) copied, 82.8041 seconds, 130 MB/s > > Thanks for your help as always. > > On Wed, Apr 20, 2011 at 5:53 PM, Joe Landman > <landman at scalableinformatics.com> wrote: >> 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 >> >
