IBM FlashSystem 710 and IBM FlashSystem 810
8
(P/E) cycles. Each FlashSystem 710 flash module has a raw capacity of approximately 340 GB, and a
usable capacity of approximately 250 GB after overprovisioning and Variable Stripe RAID overhead.
FlashSystem 810 modules use 32 nm eMLC flash chips, nominally rated for 30,000 P/E cycles. Each
FlashSystem 810 module has a raw capacity of approximately 680 GB, and a usable capacity of
approximately 500 GB after overprovisioning and Variable Stripe RAID overhead.
Important: Flash module types cannot be mixed within a system.
The following flash module protection technologies are supported:
Module-level Variable Stripe RAID
z
Error correcting codes (ECC) to provide reconstruction of data from flash chips
z
Checksums and data integrity fields protecting all internal data transfers within the system
z
Overprovisioning to enhance write endurance and decrease write amplification
z
Wear leveling algorithms that balance the number of writes among flash chips throughout the system
z
Sweeper algorithms that ensure all data within the system is read periodically to avoid data fade
z
issues
Optional Active Spare feature to manually migrate data from the failing module
z
In addition, FlashSystem 710 and FlashSystem 810 include two redundant batteries that are used to
destage lookup tables and data from RAM buffers to the flash storage in case of power failure.
Two modes of operation are supported by the systems:
RAID 0
z
JBOF (just a bunch of flash)
z
In a RAID 0 mode, data is striped across all available flash modules in a traditional RAID 0 layout (stripe
size 4 KB). Up to 1024 logical volumes (sometimes referred to as LUNs) can be created in the system,
with a minimum size of 1 GB and a maximum size of the full available system capacity.
JBOF mode allows each flash module to be treated separately without striping data across the modules.
In JBOF mode, each flash module corresponds to a single logical volume.
In either mode, failures of a single flash module containing data will most likely compromise system data
integrity for logical volumes stored on those flash modules. Data must be replicated independently of
FlashSystem 710 and FlashSystem 810 storage systems for protection against complete flash module
failures. Under the direction of the management module, the systems can coordinate data transfer
between modules; for example, to migrate data to the Active Spare module in the system, if installed.
(Note that such a data migration is a manually initiated process.)
Important: IBM recommends implementing a data replication strategy in high availability environments to
maximize data availability beyond the protections available within individual FlashSystem 710 and
FlashSystem 810 storage systems.