Adam,
What about use bache in raid1 flash devices?
- Roberto
On Fri, Apr 20, 2012 at 1:53 PM, Adam Berkan <aberkan@xxxxxxxxxx> wrote:
> If you completely lose a flash device that contains significant
> quantities of dirty data, you'll have a hard time recovering any data
> from the backing device. All of the writeback testing we've done so
> far has assumed device failures are limited to small regions of the
> device, and bcache tries to recover what it can when it encounters
> such errors. It doesn't do anything reasonable in the case of full
> device loss.
>
> I would not recommend using bcache in writeback mode anywhere where
> you can't afford to lose the whole device.
>
> Adam
>
> On Fri, Apr 20, 2012 at 8:51 AM, Brad Campbell <brad@xxxxxxxxxxxxxxx> wrote:
>>>
>> On 17/04/2012, at 4:30 PM, Kent Overstreet <koverstreet@xxxxxxxxxx> wrote:
>>
>>>
>>>
>>>> Also ... do you think that your code is production ready when using bcache
>>>> to do writeback caching ? Of course I will keep testing but I'd like to
>>>> know if you think the code by now is production ready.
>>>
>>> Yeah, it is. Test it on your configuration, etc. etc. but writeback is
>>> pretty mature and well tested at this point.
>>>
>> I've been giving serious thought to using this in a production environment. It performs well in my staging system, but my biggest concern revolves around the ultimate reliability of the ssd.
>>
>> How much testing have you performed with regard to cache device failures in a writeback scenario? I like the idea of mirroring the cache devices to replicate dirty data, however I know that is not implemented yet.
>>
>> We run a raid10 of SAS cheetahs. I'd love to mount a cache in there, but ultimately we have little information about what happens if the ssd starts to flake out. I guess more than that, there is little real information out there detailing common or potential ssd failure modes.
>>
>> I'd assume you've performed plenty of testing over the development of bcache. Can you fill us in a bit as to what to expect when things go south?
>>
>> Regards,
>> Brad--
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