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Diffstat (limited to 'drivers/staging/dst/Kconfig')
| -rw-r--r-- | drivers/staging/dst/Kconfig | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/drivers/staging/dst/Kconfig b/drivers/staging/dst/Kconfig new file mode 100644 index 000000000000..448d342ac2a2 --- /dev/null +++ b/drivers/staging/dst/Kconfig @@ -0,0 +1,67 @@ +config DST + tristate "Distributed storage" + depends on NET && CRYPTO && SYSFS && BLK_DEV + select CONNECTOR + ---help--- + DST is a network block device storage, which can be used to organize + exported storage on the remote nodes into the local block device. + + DST works on top of any network media and protocol; it is just a matter + of configuration utility to understand the correct addresses. The most + common example is TCP over IP, which allows to pass through firewalls and + create remote backup storage in a different datacenter. DST requires + single port to be enabled on the exporting node and outgoing connections + on the local node. + + DST works with in-kernel client and server, which improves performance by + eliminating unneded data copies and by not depending on the version + of the external IO components. It requires userspace configuration utility + though. + + DST uses transaction model, when each store has to be explicitly acked + from the remote node to be considered as successfully written. There + may be lots of in-flight transactions. When remote host does not ack + the transaction it will be resent predefined number of times with specified + timeouts between them. All those parameters are configurable. Transactions + are marked as failed after all resends complete unsuccessfully; having + long enough resend timeout and/or large number of resends allows not to + return error to the higher (FS usually) layer in case of short network + problems or remote node outages. In case of network RAID setup this means + that storage will not degrade until transactions are marked as failed, and + thus will not force checksum recalculation and data rebuild. In case of + connection failure DST will try to reconnect to the remote node automatically. + DST sends ping commands at idle time to detect if remote node is alive. + + Because of transactional model it is possible to use zero-copy sending + without worry of data corruption (which in turn could be detected by the + strong checksums though). + + DST may fully encrypt the data channel in case of untrusted channel and implement + strong checksum of the transferred data. It is possible to configure algorithms + and crypto keys; they should match on both sides of the network channel. + Crypto processing does not introduce noticeble performance overhead, since DST + uses configurable pool of threads to perform crypto processing. + + DST utilizes memory pool model of all its transaction allocations (it is the + only additional allocation on the client) and server allocations (bio pools, + while pages are allocated from the slab). + + At startup DST performs a simple negotiation with the export node to determine + access permissions and size of the exported storage. It can be extended if + new parameters should be autonegotiated. + + DST carries block IO flags in the protocol, which allows to transparently implement + barriers and sync/flush operations. Those flags are used in the export node where + IO against the local storage is performed, which means that sync write will be sync + on the remote node too, which in turn improves data integrity and improved resistance + to errors and data corruption during power outages or storage damages. + + Homepage: http://www.ioremap.net/projects/dst + Userspace configuration utility and the latest releases: http://www.ioremap.net/archive/dst/ + +config DST_DEBUG + bool "DST debug" + depends on DST + ---help--- + This option will enable HEAVY debugging of the DST. + Turn it on ONLY if you have to debug some really obscure problem. |