Re: swapcache-style cache?

----- Цитат от Andrea Suisani (sickpig(at)opinioni(dot)net), на 28.02.2012 в 09:54 -----

> On 02/28/2012 04:52 AM, Rob Wultsch wrote:
>> On Wed, Feb 22, 2012 at 2:31 PM, james<james(at)mansionfamily(dot)plus(dot)com> wrote:
>>> Has anyone considered managing a system like the DragonFLY swapcache for a
>>> DBMS like PostgreSQL?
>>>
>>
>> https://www.facebook.com/note.php?note_id=388112370932
>>
>
> in the same vein:
>
> http://bcache.evilpiepirate.org/
>
> from the main page:
>
> "Bcache is a patch for the Linux kernel to use SSDs to cache other block devices. It's analogous to L2Arc for ZFS,
> but Bcache also does writeback caching, and it's filesystem agnostic. It's designed to be switched on with a minimum
> of effort, and to work well without configuration on any setup. By default it won't cache sequential IO, just the random
> reads and writes that SSDs excel at. It's meant to be suitable for desktops, servers, high end storage arrays, and perhaps
> even embedded."
>
> it was submitted to linux kernel mailing list a bunch of time, the last one:
>
> https://lkml.org/lkml/2011/9/10/13
>
>
> Andrea
>

I am successfully using facebook's flashchache in write-through mode - so it speeds only reads. I have seen 3 times
increase on TPS for databases that do not fit in RAM. I am using Intel X-25E over RAID10 of 4 SAS disks. I have tested also
writeback mode but the gain is not so huge and there is a considerable risk for loosing all your data if/when the SSD fails.

Best regards

--
Luben Karavelov