[Gluster-devel] Data Classification: would it be possible to have a RAM-disk as caching tier?

[Dan Lambright]

The tiering code ought to work if the underlying volume is a RAM disk.  Its like any other Gluster brick.  But as mentioned, this would be unsafe for their data. If the power went out, anything in the RAM disk would be lost. I think a pure "read cache" may be a better option for RAM disks. This is the route companies like NimbleStorage and Infinio went. Read caches are something the feature may support in the future.

Dan

----- Original Message -----
> From: "Joseph Fernandes" <josferna at redhat.com>
> To: "Niels de Vos" <ndevos at redhat.com>
> Cc: gluster-devel at gluster.org, "Dan Lambright" <dlambrig at redhat.com>
> Sent: Monday, February 16, 2015 5:54:15 AM
> Subject: Re: Data Classification: would it be possible to have a RAM-disk as caching tier?
> 
> Hi Niels,
> 
> Well the idea is good, RAM-Disk would fastest and with no extra cost +
> We may have gluster brick from RAM-Disk[1]
> The one and the biggest challenge would be durability of data on RAM-Disks
> Using RAM for caching is good, as the cache will have only the copy of the
> original data
> but in case of tiering, the original data sits on the tier(not the copy).
> 
> Dan your thoughts.
> 
> Thanks,
> Joe
> 
> 1. https://lists.gnu.org/archive/html/gluster-devel/2013-05/msg00118.html
> 
> ----- Original Message -----
> From: "Niels de Vos" <ndevos at redhat.com>
> To: gluster-devel at gluster.org
> Cc: "Dan Lambright" <dlambrig at redhat.com>, "Joseph Fernandes"
> <josferna at redhat.com>
> Sent: Monday, February 16, 2015 4:14:37 PM
> Subject: Data Classification: would it be possible to have a RAM-disk as
> caching tier?
> 
> Hi guys,
> 
> at FOSDEM one of our users spoke to me about their deployment and
> environment. It seems that they have a *very* good deal with their
> hardware vendor, which makes it possible to stuff their servers full
> with RAM for a minimal difference of the costs.
> 
> They expressed interest in having a RAM-disk as caching tier on the
> bricks. Would a configuration like this be possible with the
> data-classification feature [1]?
> 
> Thanks,
> Niels
> 
> 1.
> http://www.gluster.org/community/documentation/index.php/Features/data-classification
>