[Gluster-users] Performance

[Mohit Anchlia]

What are some of the good controller cards would you recommend for SAS
drives? Dell and Areca is what I am seeing most suggested online.

On Tue, Apr 26, 2011 at 4:43 PM, Mohit Anchlia <mohitanchlia at gmail.com> wrote:
> In your experience does it really help having journal on different
> disk? Just trying to see if it's worth the effort. Also, Gluster also
> recommends creating mkfs with larger blocks mkfs -I 256
>
> As always thanks for the suggestion.
>
> On Tue, Apr 26, 2011 at 4:31 PM, Joe Landman
> <landman at scalableinformatics.com> wrote:
>> On 04/26/2011 05:48 PM, Mohit Anchlia wrote:
>>>
>>> I am not sure how valid this performance url is
>>>
>>>
>>> http://www.gluster.com/community/documentation/index.php/Guide_to_Optimizing_GlusterFS
>>>
>>> Does it make sense to separate out the journal and create mkfs -I 256?
>>>
>>> Also, if I already have a file system on a different partition can I
>>> still use it to store journal from other partition without corrupting
>>> the file system?
>>
>> Journals are small write heavy.  You really want a raw device for them.  You
>> do not want file system caching underneath them.
>>
>> Raw partition for an external journal is best.  Also, understand that ext*
>> suffers badly under intense parallel loads.  Keep that in mind as you make
>> your file system choice.
>>
>>>
>>> On Thu, Apr 21, 2011 at 7:23 PM, Joe Landman
>>> <landman at scalableinformatics.com>  wrote:
>>>>
>>>> On 04/21/2011 08:49 PM, Mohit Anchlia wrote:
>>>>>
>>>>> After lot of digging today finaly figured out that it's not really
>>>>> using PERC controller but some Fusion MPT. Then it wasn't clear which
>>>>
>>>> PERC is a rebadged LSI based on the 1068E chip.
>>>>
>>>>> tool it supports. Finally I installed lsiutil and was able to change
>>>>> the cache size.
>>>>>
>>>>> [root at dsdb1 ~]# lspci|grep LSI
>>>>> 02:00.0 SCSI storage controller: LSI Logic / Symbios Logic SAS1068E
>>>>> PCI-Express Fusion-MPT SAS (rev 08)
>>>>
>>>>  This looks like PERC.  These are roughly equivalent to the LSI 3081
>>>> series.
>>>>  These are not fast units.  There is a variant of this that does RAID6,
>>>> its
>>>> usually available as a software update or plugin module (button?) to
>>>> this.
>>>>  I might be thinking of the 1078 chip though.
>>>>
>>>>  Regardless, these are fairly old designs.
>>>>
>>>>
>>>>> [root at dsdb1 ~]# dd if=/dev/zero of=/data/big.file bs=128k count=40k
>>>>> oflag=direct
>>>>> 1024+0 records in
>>>>> 1024+0 records out
>>>>> 134217728 bytes (134 MB) copied, 0.742517 seconds, 181 MB/s
>>>>>
>>>>> I compared this with SW RAID mdadm that I created yesterday on one of
>>>>> the servers and I get around 300MB/s. I will test out first with what
>>>>> we have before destroying and testing with mdadm.
>>>>
>>>> So the software RAID is giving you 300 MB/s and the hardware 'RAID' is
>>>> giving you ~181 MB/s?  Seems a pretty simple choice :)
>>>>
>>>> BTW: The 300MB/s could also be a limitation of the PCIe channel
>>>> interconnect
>>>> (or worse, if they hung the chip off a PCIx bridge).  The motherboard
>>>> vendors are generally loathe to put more than a few PCIe lanes for
>>>> handling
>>>> SATA, Networking, etc.  So typically you wind up with very low powered
>>>> 'RAID' and 'SATA/SAS' on the motherboard, connected by PCIe x2 or x4 at
>>>> most.  A number of motherboards have NICs that are served by a single
>>>> PCIe
>>>> x1 link.
>>>>
>>>>> Thanks for your help that led me to this path. Another question I had
>>>>> was when creating mdadm RAID does it make sense to use multipathing?
>>>>
>>>> Well, for a shared backend over a fabric, I'd say possibly.  For an
>>>> internal
>>>> connected set, I'd say no.  Given what you are doing with Gluster, I'd
>>>> say
>>>> that the additional expense/pain of setting up a multipath scenario
>>>> probably
>>>> isn't worth it.
>>>>
>>>> Gluster lets you get many of these benefits at a higher level in the
>>>> stack.
>>>>  Which to a degree, and in some use cases, obviates the need for
>>>> multipathing at a lower level.  I'd still suggest real RAID at the lower
>>>> level (RAID6, and sometimes RAID10 make the most sense) for the backing
>>>> store.
>>>>
>>>>
>>>> --
>>>> 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
>>
>