Are there plans to add provisioning of spare bricks in a replicated (or
distributed-replicated) configuration? E.g., when a brick in a mirror
set dies, the system rebuilds it automatically on a spare, similar to
how it’d done by RAID controllers.
Nor would it only improve the practical reliability, especially of large
clusters, but it’d also make it possible to make better-performing
clusters off less expensive components. For example, instead of having
slow RAID5 bricks on expensive RAID controllers one uses cheap HBA-s and
stripes a few disks per brick in RAID0 – that’s faster for writes than
RAID 5/6 by an order of magnitude (and, by the way, should improve
rebuild times in Gluster many are complaining about.).A failure of one
such striped brick is not catastrophic in a mirrored Gluster – but it’s
better to have spare bricks standing by strewn across cluster heads.
A more advanced setup at a hardware level involves creating “hybrid
disks” whereas HDD vdisks are cached by enterprise-class SSD-s.It works
beautifully and makes HDD-s amazingly fast for random transactions.The
technology’s become widely available for many $500 COTS
controllers.However, it is not widely known that the results with HDD-s
in RAID0 under SSD cache are 10 to 20 (!!) times better than with RAID 5
or 6.