[Gluster-users] Performance

[Mohit Anchlia]

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
>