On 8 September 2017 at 12:13, Valeri Galtsev <galtsev@xxxxxxxxxxxxxxxxx> wrote:
>
> On Fri, September 8, 2017 11:07 am, Stephen John Smoogen wrote:
>> On 8 September 2017 at 11:00, Valeri Galtsev <galtsev@xxxxxxxxxxxxxxxxx>
>> wrote:
>>>
>>> On Fri, September 8, 2017 9:48 am, hw wrote:
>>>> m.roth@xxxxxxxxx wrote:
>>>>> hw wrote:
>>>>>> Mark Haney wrote:
>>>>> <snip>
>>>>>>> BTRFS isn't going to impact I/O any more significantly than, say,
>>>>>>> XFS.
>>>>>>
>>>>>> But mdadm does, the impact is severe. I know there are ppl saying
>>>>>> otherwise, but I´ve seen the impact myself, and I definitely
>>>>>> don´t
>>>>>> want
>>>>>> it on that particular server because it would likely interfere with
>>>>>> other services.
>>>>> <snip>
>>>>> I haven't really been following this thread, but if your requirements
>>>>> are
>>>>> that heavy, you're past the point that you need to spring some money
>>>>> and
>>>>> buy hardware RAID cards, like LSI, er, Avago, I mean, who's bought
>>>>> them
>>>>> more recently?
>>>>
>>>> Heavy requirements are not required for the impact of md-RAID to be
>>>> noticeable.
>>>>
>>>> Hardware RAID is already in place, but the SSDs are "extra" and, as I
>>>> said,
>>>> not suited to be used with hardware RAID.
>>>
>>> Could someone, please, elaborate on the statement that "SSDs are not
>>> suitable for hardware RAID".
>>>
>>
>> It will depend on the type of SSD and the type of hardware RAID. There
>> are at least 4 different classes of SSD drives with different levels
>> of cache, write/read performance, number of lifetime writes, etc.
>> There are also multiple types of hardware RAID. A lot of hardware RAID
>> will try to even out disk usage in different ways. This means 'moving'
>> the heavily used data from slow parts to fast parts etc etc.
>
> Wow, you learn something every day ;-) Which hardware RAIDs do these
> moving of data (manufacturer/model, please - believe it or not I never
> heard of that ;-). And "slow part" and "fast part" of what are data being
> moved between?
>
> Thanks in advance for tutorial!
>
I thought it was HP who had these, but I can't find it.. which means
without references... I get an F. My apologies on that. Thank you for
keeping me honest.
--
Stephen J Smoogen.
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