As the size of Dispersed Storage Networks in operation grow larger, what is the optimum maximum number of Slices for each data element stored on the dsNet?

The “Width” of a “Vault” on a dsNet determines the number of dispersed Slices that are physically stored for each data element in that vault.  For example, a typical block interface typically uses 4K blocks, so the dsNet block interface presents an interface that stores and retrieves 4K blocks.  (The dsNet iSCSI target uses this block interface.)

When storing a 4K block, the dsNet creates a number of slices equal to the width set for the associated vault on the dsNet.  Each of these slices are then typically stored on different Slicestors.  Most of the initial dsNets used 8 Slicestors and set the width of each vault to 8.  Although the information dispersal algorithms we use can mathematically support any width (and our implementation can be configured with widths up to 256), the initial commercial release only supported 8 as the width since that was a width for which we had completed comprehensive testing.  We’re now beginning comprehensive testing with 16 wide dsNets and then expect to test wider widths:  32, 64, maybe 128 or higher.

In smaller dsNets, it is common for the width of the vault(s) on the dsNet to equal the number of Slicestors, but as dsNets grow the number of Slicestors will exceed the width of any vault on that dsNet.

Many dsNets will store and distribute at least Petabytes of data using more thousands or more Slicestors and will often use different widths (and threshold settings) for various vaults stored on those dsNets.  We expect that the widths for those vaults will vary from 8 to 64 or perhaps 128, but will be significantly less than the total number of Slicestors on the dsNet.

Chris