Re: support for external persistent cache

[Roberto Spadim <roberto@spadim.com.br>]

look this:
http://www.ramsan.com/products/4
http://www.ramsan.com/products/2


2011/1/19 Roberto Spadim <roberto@spadim.com.br>:
> don´t forget that you can use ramdisks.... just read how to select the
> right memory, and the right position before initialize you ramdisk
>
> 2011/1/19 Roberto Spadim <roberto@spadim.com.br>:
>> ok, your hardware have:
>> cpu, memory, disk controller, disks
>>
>> and you computer have:
>> cpu, memory, disk controler (your hardware)
>>
>> if your computer cache don´t sync to your disk controller you will
>> lose information....
>>
>> check that *memory, is the volatille memory and *disk controller is
>> the non volatille memory
>> if you tell me that you will never have a *memory, and you have always
>> a non volatille memory, no problem, you will never need a kernel
>> load... just a boot loader that read previous memory information and
>> start in that point... why don´t do this? non volatille memory is not
>> as fast as volatille memory
>> got the problem?
>>
>>
>> 2011/1/19 Cory Coager <ccoager@gmail.com>:
>>> On Wed, Jan 19, 2011 at 01:19:18PM -0200, Roberto Spadim wrote:
>>>> ok,
>>>> but if you don?t sync file system (remove from memory and put in disk
>>>> controller)
>>>> you will lost information with or without a batery
>>>>
>>>> how to don?t lose information?
>>>> don?t power down you memory,cpu, disk controller (sata controler, raid
>>>> controller, or anyother) and disks (does it have a batery? a super
>>>> capacitor?)
>>>> if you power down, be sure that all memory was send to disk controller
>>>> and that disk controller have energy (batery or capacitor) to send
>>>> information to disks (they need batery or capacitor too)
>>>>
>>>> right?
>>>> so, a ups can power cpu, memory, disk controller and disks with only
>>>> one batery (not a batery for each device cpu,memory,disk,disk
>>>> controller)
>>>> the best world could be a non volatile memory (250mb/s flash 4kb
>>>> block) with the speed of volatile memory (10000mb/s ddr3 i don?t know
>>>> the block size)
>>>
>>> It would have to work the same as a hardware RAID controller.
>>> Information is first written to the cache then synced to the
>>> disk.  If the data is in the cache but not on the disk, the
>>> machine loses power, next boot up the software raid would need a
>>> way to flush the data from the ram disk to the disk.  Of course
>>> this would require the battery be in working condition, as with
>>> any hardware.
>>>
>>> Hopefully I've explained that well enough.  Perhaps it will be
>>> better to see the hardware I'm talking about:
>>> http://techreport.com/articles.x/16255
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
>>> the body of a message to majordomo@vger.kernel.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>
>>
>>
>>
>> --
>> Roberto Spadim
>> Spadim Technology / SPAEmpresarial
>>
>
>
>
> --
> Roberto Spadim
> Spadim Technology / SPAEmpresarial
>



-- 
Roberto Spadim
Spadim Technology / SPAEmpresarial
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html