[OpenIndiana-discuss] Poor relative performance of SAS over SATA drives

[Jason J. W. Williams]

Is the card hosting any SATA and SAS drives on the same port, or are
they segregated SAS on one and SATA on the other?

-J

On Wed, Oct 26, 2011 at 9:01 AM, weiliam.hong <weiliam.hong at gmail.com> wrote:
> Greetings,
>
> I have a fresh installation of OI151a:
> - SM X8DTH, 12GB RAM, LSI 9211-8i (latest IT-mode firmware)
> - pool_A : SG ES.2 Constellation (SAS)
> - pool_B : WD RE4 (SATA)
> - no settings in /etc/system
>
>
> *zpool status output*
> -------------------
> admin at openindiana:~# zpool status
>  pool: pool_A
>  state: ONLINE
>  scan: none requested
> config:
>
>        NAME                       STATE     READ WRITE CKSUM
>        pool_A                     ONLINE       0     0     0
>          mirror-0                 ONLINE       0     0     0
>            c7t5000C50035062EC1d0  ONLINE       0     0     0
>            c8t5000C50034C03759d0  ONLINE       0     0     0
>
>  pool: pool_B
>  state: ONLINE
>  scan: none requested
> config:
>
>        NAME                       STATE     READ WRITE CKSUM
>        pool_B                     ONLINE       0     0     0
>          mirror-0                 ONLINE       0     0     0
>            c1t50014EE057FCD628d0  ONLINE       0     0     0
>            c2t50014EE6ABB89957d0  ONLINE       0     0     0
>
>
> *Load generation via 2 concurrent dd streams:*
> --------------------------------------------------
> dd if=/dev/zero of=/pool_A/bigfile bs=1024k count=1000000
> dd if=/dev/zero of=/pool_B/bigfile bs=1024k count=1000000
>
>
> *Initial Observation*
> -------------------
>
>               capacity     operations    bandwidth
> pool        alloc   free   read  write   read  write
> ----------  -----  -----  -----  -----  -----  -----
> pool_A      1.68G  2.72T      0    652      0  73.4M
>  mirror    1.68G  2.72T      0    652      0  73.4M
>    c7t5000C50035062EC1d0      -      -      0    619      0  73.4M
>    c8t5000C50034C03759d0      -      -      0    619      0  73.4M
> ----------  -----  -----  -----  -----  -----  -----
> pool_B      1.54G  1.81T      0  1.05K      0   123M
>  mirror    1.54G  1.81T      0  1.05K      0   123M
>    c1t50014EE057FCD628d0      -      -      0  1.02K      0   123M
>    c2t50014EE6ABB89957d0      -      -      0  1.01K      0   123M
>
> *
> 10-15mins later*
> ------------=--
>
>               capacity     operations    bandwidth
> pool        alloc   free   read  write   read  write
> ----------  -----  -----  -----  -----  -----  -----
> pool_A      15.5G  2.70T      0     50      0  6.29M
>  mirror    15.5G  2.70T      0     50      0  6.29M
>    c7t5000C50035062EC1d0      -      -      0     62      0  7.76M
>    c8t5000C50034C03759d0      -      -      0     50      0  6.29M
> ----------  -----  -----  -----  -----  -----  -----
> pool_B      28.0G  1.79T      0  1.07K      0   123M
>  mirror    28.0G  1.79T      0  1.07K      0   123M
>    c1t50014EE057FCD628d0      -      -      0  1.02K      0   123M
>    c2t50014EE6ABB89957d0      -      -      0  1.02K      0   123M
>
>
>
> Questions:
> 1. Why does SG SAS drives degrade to <10 MB/s while WD RE4 remain consistent
> at >100MB/s after 10-15 min?
> 2. Why does SG SAS drive show only 70+ MB/s where is the published figures
> are > 100MB/s refer here
> <http://www.seagate.com/www/en-us/products/enterprise-hard-drives/constellation-es/constellation-es-2/#tTabContentSpecifications>?
> 3. All 4 drives are connected to a single HBA, so I assume the mpt_sas
> driver is used. Are SAS and SATA drives handled differently ?
>
>
> This is a test server, so any ideas to try and help me understand greatly
> appreciated.
>
>
> Many thanks,
> WL
>
>
>
>
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