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Figure 5: SanDisk Replication
If applicable, the SSDs in a Membrain node can be configured using RAID 5 to further increase
node availability. This allows the node to tolerate the failure of a single SSD without a loss of
service. When using SSDs that are hot-swappable, a defective SSD can be replaced without
stopping the Memcached / NoSQL service.
Using Backup and Restore to Protect Against Data Corruption or Loss
Many applications need to back up the contents of Memcached or key-value stores to recover
from user errors or application-driven data corruption, for full recovery and restore from
catastrophic data loss, for warming the caches of new servers before bringing them online, and
for logging.
Membrain supports full and incremental backup and restore of persistent containers to hard
disk drives. A full backup is a logical copy of all objects in a container. An incremental backup
is a logical copy of objects in a container that are new or have changed since the previous
backup, including a logical representation of deleted objects. A full backup is taken to start a
new backup “series”, which contains the full backup plus zero or more incremental backups.
There is no limit to the number of incremental backups in a series. Backups can be scheduled at
regular intervals.
Backups can be taken while the server is still servicing client requests. In this case, data written
by a client after the backup is started may or may not be included in the backup.
Restoring a backup is the process of replaying backup streams to a server. A backup can be
restored to any container. The target container must already exist and have sufficient space
before the restore is started. The container can be restored to an arbitrary checkpoint within
the series. See Figure 6.
Figure 6: SanDisk Backup and Restore
gets/sets
to key set 0
Master 0
Synchronous Replication
Master 1
VIP group 0
VIP group 1
gets/sets
to key set 1
Normal Operation
Master 0
Re-sync data
Synchronous Replication
Master 1
VIP group 1
gets/sets
to key sets 0
and 1
Recovery
Master 1
Service
Interruption
VIP group 0
VIP group 0
VIP group 1
gets/sets
to key set 1
Failover
Container
TCP/UDP Port
TCP/UDP Port
Hard Drive
Hard Drive
TCP/UDP Port
TCP/UDP Port
Cap:
128GB
Non-Persistent
Cache Mode
Data:
Thumbnails
Container
Cap:
64GB
Persistent
Cache Mode
Data:
Queries
Container
Cap:
64GB
Persistent
Store Mode
Data:
Cookies
Container
Cap:
64GB
Persistent
Store Mode
Data:
Photos
Backup
Enable backup
per container
Full or
incremental
backup
Enable up to
8 parallel
streams
Choose
backup interval
Container
TCP/UDP Port
TCP/UDP Port
TCP/UDP Port
TCP/UDP Port
Cap:
128GB
Non-Persistent
Cache Mode
Data:
Thumbnails
Container
Cap:
64GB
Persistent
Cache Mode
Data:
Queries
Container
Cap:
64GB
Persistent
Store Mode
Data:
Cookies
Container
Cap:
64GB
Persistent
Store Mode
Data:
Photos
Restore
Restore to
empty container
Restore to any
previous full or
incremental
backup point
