Wednesday, April 30, 2014

Seagate Kinetic Open Storage

It's primarily for Object Storage in which drive is key/value server with Ethernet connectivity.

The Kinetic Drive API provides following capability
1) Kinetic Key-Value Access
2) Key Ordering and Iterators
3) Cluster Management
4) Drive Management
5) Security Management

Since storage are no longer aggregated behind a server, this enable Software defined storage in which any storage any drive can be provisioned to any process in the cluster.

1st Generation Kinetic Drive Limitation

4KB Key and 1 MB Values.. (Drive Management handles the limitation)
2 1GB ethernet over SGMII (Mechanically identical as SAS connector).

So what is Kinetic ??
1) A new classs of key/value Ethernet Drives + Open API and series of libraries

Drives talks in keys and value as opposed to blocks. They do get, put and deletes.

Drive efficiently manages
1) Managing key ordering
2) QOS
3) Policy based 'drive-2-drive' data migration.
4) Handling of partial device failures and other management.
5) Data Security

This new model where legacy software and hardware are removed and thus storage can truly be disaggregated from compute, so Racks will be more dense, fans are minimized.

Kinetic drive are native key/value stores. This shifts the burden of maintaining the space mapping from filesystem to the drive itself. Application needs to only put and get objects and no longer need to guess the LBA layout or prescribe data location.

Advantage of Kinetic Disk Drive:
        1) Multiple Client with Shared Data.
        2) Data Migration between 2 Kinetic Drive.

Kinetic Library API
   a) Admin  API : getLog, setSecurity, setup
   b) Client API : Synchronous, Asynchronous, put, get, delete, getNext, getPrevious, getKeyRange, getMetadata.

Kinetic Simulator
    Simulator API provides a simulator boot-strap class used for application to start a new Instance of the simulator as a drive.
    Default Port: 8123 as service port

Simulator Setup
1) Download Eclipse IDE from

2)  extract eclipse-java-kepler-SR2-linux-gtk-x86_64.tar.gz

3) Start eclipse

4) Import Kinetic Git hub repositories... (Make sure you have account with Seagate to access Kinetic Git Hub)

Download Apache-Maven

Run mvn clean package in Kinetic Directory.

Set classpath environment variable.. make sure set jar file created by maven.

export CLASSPATH=/home/ssd/kinetic/Kinetic-Preview/lib/Kinetic-


Saturday, April 19, 2014

mmap caching issue on ARM.

This issue observed on ARM, when doing to map kernel allocated memory 
i.e via __get_free_pages.
Kernel module updating some counters are not immediately reflected 
to userspace code.
The following code in the userspace program is used to clear the 
cache after read operation. 
/* */
void clear_arm_cache(const char *start_addr , const char *end_addr)
 const int syscall = 0xf0002;
 __asm __volatile (
  "mov  r0, %0\n"   
  "mov  r1, %1\n"
  "mov  r7, %2\n"
  "mov     r2, #0x0\n"
  "svc     0x00000000\n"
  : "r" (begin), "r" (end), "r" (syscall)
  : "r0", "r1", "r7"