[occi-wg] Finished first pass over FeatureMatrix

[Gary Mazz]

Chuck,

Raid is for availability when there is a disk "failure".  If there is 
data corruption on the disk due to raid controller, multi-bit errors on 
the interconnect or corruption due to a non-failure mode related disk 
defect; raid has no hope of saving your skin, this a common mis-conception.

As for interconnects, my two favorites are SAS and infiniband (now 
clocked @ 40gb/s).

It is not uncommon for see scsi read command to data latencies on a raid 
system in excess of 1s. You will see much better performance results if 
you load up your system with 4gb ECC of disk cache. ;) 

-g

Chuck Wegrzyn wrote:
> Whoa...RAID has all to do with data integrity and performance. I will
> buy that on NAS or SAN.
>
> Chuck Wegrzyn
>
> Gary Mazz wrote:
>   
>> I like Sam's approach, especially the "expressed as what". The whole 
>> idea of SANx or RAIDxx can be overwhelming and confusing to the 
>> customers. Especially, when raid or sans have very little to do with 
>> data integrity or performance.
>>
>> I would prefer to see something that falls in line with SLAs as way to 
>> describe storage services.
>>
>> -gary
>>
>> Sam Johnston wrote:
>>     
>>> On Mon, Jun 15, 2009 at 5:29 PM, Richard Davies 
>>> <richard at daviesmail.org <mailto:richard at daviesmail.org>> wrote:
>>>
>>>     There's a strong argument for clouds to support both. Persistent
>>>     storage is
>>>     typically on SAN where it can be accessed from all virtualization
>>>     hosts when
>>>     the server is stopped and restarted. Ephemeral storage is
>>>     typically on local
>>>     disk, which is much faster but unavailable after the server is
>>>     stopped and
>>>     restarted on a different machine.
>>>
>>>
>>> Right, there are many different possibilities for storage that should 
>>> arguably be specified by user requirement ("what" e.g. "geographically 
>>> redundant") rather than technology ("how" e.g. "RAID 10"). The three 
>>> main options I see for "local" storage are:
>>>
>>>     * Ephemeral which is lost when the machine stops (thus simplifying
>>>       infrastructure and reducing costs)
>>>     * Local storage which may or may not exist next time you need it
>>>       (good for caching configurations, calculations and so on but not
>>>       much else)
>>>     * Redundant storage which will probably survive failures (e.g. SAN)
>>>     * HA storage which is geographically distributed, backed up, etc.
>>>       and which you can rely on.
>>>
>>> Of course the different levels would carry different costs and be 
>>> useful for different purposes. We just need to find a simple way for 
>>> users to get and set their preferences (whether expressed as "what" or 
>>> "how").
>>>
>>> Sam
>>>
>>> ------------------------------------------------------------------------
>>>
>>> _______________________________________________
>>> occi-wg mailing list
>>> occi-wg at ogf.org
>>> http://www.ogf.org/mailman/listinfo/occi-wg
>>>   
>>>       
>> _______________________________________________
>> occi-wg mailing list
>> occi-wg at ogf.org
>> http://www.ogf.org/mailman/listinfo/occi-wg
>>     
>
>
>