[OpenIndiana-discuss] Poor relative performance of SAS overSATA drives

[Jason Matthews]

What is the link speed of the SAS drives as reported by the controller?

j.

-----Original Message-----
From: Hong Wei Liam [mailto:weiliam.hong at gmail.com] 
Sent: Wednesday, October 26, 2011 4:59 PM
To: Discussion list for OpenIndiana
Subject: Re: [OpenIndiana-discuss] Poor relative performance of SAS overSATA
drives

I had initially  tried only having the SAS drives installed with the same
results.

Later, the SATA drives were added in for comparison.

Regards,
WL


On Oct 27, 2011, at 2:27 AM, Jason J. W. Williams wrote:

> 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/constellat
ion-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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>> OpenIndiana-discuss at openindiana.org
>> http://openindiana.org/mailman/listinfo/openindiana-discuss
>> 
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