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From Ran User <ranuse...@gmail.com>
Subject Re: idea drive layout - 4 drives + RAID question
Date Tue, 30 Oct 2012 03:33:13 GMT
Have you considered running RAID 10 for the data drives to improve MTBF?

On one hand Cassandra is handling redundancy issues, on the other
hand, reducing the frequency of dealing with failed nodes
is attractive if cheap (switching RAID levels to 10).

We have no experience with software RAID (have always used hardware raid
with BBU).  I'm assuming software RAID 1 or 10 (the mirroring part) is
inherently reliable (perhaps minus some edge case).

On Tue, Oct 30, 2012 at 1:07 AM, Tupshin Harper <tupshin@tupshin.com> wrote:

> I would generally recommend 1 drive for OS and commit log and 3 drive raid
> 0 for data. The raid does give you good performance benefit, and it can be
> convenient to have the OS on a side drive for configuration ease and better
> MTBF.
>
> -Tupshin
> On Oct 29, 2012 8:56 PM, "Ran User" <ranuser99@gmail.com> wrote:
>
>> I was hoping to achieve approx. 2x IO (write and read) performance via
>> RAID 0 (by accepting a higher MTBF).
>>
>> Do believe the performance gains of RAID0 are much lower and/or are not
>> worth it vs the increased server failure rate?
>>
>> From my understanding, RAID 10 would achieve the read performance
>> benefits of RAID 0, but not the write benefits.  I'm also considering RAID
>> 10 to maximize server IO performance.
>>
>> Currently, we're working with 1 CF.
>>
>>
>> Thank you
>>
>> On Mon, Oct 29, 2012 at 11:51 PM, Timmy Turner <timm.turn@gmail.com>wrote:
>>
>>> I'm not sure whether the raid 0 gets you anything other than headaches
>>> should one of the drives fail. You can already distribute the
>>> individual Cassandra column families on different drives by just
>>> setting up symlinks to the individual folders.
>>>
>>> 2012/10/30 Ran User <ranuser99@gmail.com>:
>>> > For a server with 4 drive slots only, I'm thinking:
>>> >
>>> > either:
>>> >
>>> > - OS (1 drive)
>>> > - Commit Log (1 drive)
>>> > - Data (2 drives, software raid 0)
>>> >
>>> > vs
>>> >
>>> > - OS  + Data (3 drives, software raid 0)
>>> > - Commit Log (1 drive)
>>> >
>>> > or something else?
>>> >
>>> > also, if I can spare the wasted storage, would RAID 10 for cassandra
>>> data
>>> > improve read performance and have no effect on write performance?
>>> >
>>> > Thank you!
>>>
>>
>>

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