[Users] flashcache

[Kir Kolyshkin]

On 07/08/2014 11:54 PM, Pavel Snajdr wrote:
> On 07/08/2014 07:52 PM, Scott Dowdle wrote:
>> Greetings,
>>
>> ----- Original Message -----
>>> (offtopic) We can not use ZFS. Unfortunately, NAS with something like
>>> Nexenta is to expensive for us.
>> From what I've gathered from a few presentations, ZFS on Linux (http://zfsonlinux.org/) is as stable but more performant than it is on the OpenSolaris forks... so you can build your own if you can spare the people to learn the best practices.
>>
>> I don't have a use for ZFS myself so I'm not really advocating it.
>>
>> TYL,
>>
> Hi all,
>
> we run tens of OpenVZ nodes (bigger boxes, 256G RAM, 12cores+, 90 CTs at
> least). We've used to run ext4+flashcache, but ext4 has proven to be a
> bottleneck. That was the primary motivation behind ploop as far as I know.
>
> We've switched to ZFS on Linux around the time Ploop was announced and I
> didn't have second thoughts since. ZFS really *is* in my experience the
> best filesystem there is at the moment for this kind of deployment  -
> especially if you use dedicated SSDs for ZIL and L2ARC, although the
> latter is less important. You will know what I'm talking about when you
> try this on boxes with lots of CTs doing LAMP load - databases and their
> synchronous writes are the real problem, which ZFS with dedicated ZIL
> device solves.
>
> Also there is the ARC caching, which is smarter then linux VFS cache -
> we're able to achieve about 99% of hitrate at about 99% of the time,
> even under high loads.
>
> Having said all that, I recommend everyone to give ZFS a chance, but I'm
> aware this is yet another out-of-mainline code and that doesn't suit
> everyone that well.
>

Are you using per-container ZVOL or something else?