[Gluster-users] two questions regarding glusterfs cluster: tierd storage and hotspare brick

[Vijay Bellur]

On 12/28/2014 02:07 PM, Zhu,Chao wrote:
> hi, all,
>      We are using gluster 3.5.2 on standard 3TB*12 machines, some hosts
> also got SSD on the machines as well;
> two questions:
> 1. Is there mature solution, I can use the SSD as the write cache for
> sata disks? So I can combine the power of SSD as write cache(and even
> read cache), and the capacity provided by SATA disks?
>

Data tiering feature being developed for 3.7 can help here. More details 
about tiering can be found in this larger proposal for data 
classification [1].

> 2. As sata disks fails often(relatively, when you got lots of disks...),
> each time a disk fails, i will have to manually replace the disks, and
> replace the bricks;
>      Can we setup spare bricks?
>       Say, I have 12*3TB sata disks, I only use 10 disks as 10 Bricks
> with data on it, and have 2 disks configured with filesystem, as part of
> volume, without putting data on the brick/filesystem? So in case on
> brick fails, this brick automatically replace that failed disks? Just
> like hotspare in raid?

There's no automatic mechanism to do this from the CLI today. GlusterFS 
has the ability to detect brick failures [2] and also to perform an 
online replacement of a brick in a volume. By combining these two 
features and defining a mechanism in management to add/remove spare 
bricks, this functionality can be achieved.

Regards,
Vijay

[1] 
http://www.gluster.org/community/documentation/index.php/Features/data-classification

[2] 
http://www.gluster.org/community/documentation/index.php/Features/Brick_Failure_Detection