+ 12/02 meeting 張皓翔 陳俞任

+ Synology DS207+ CPUARM 926EJ-S IP Userroot/admin Passwordcsie504 Firmware latest updatedDSM Modules installedarm-bootstrap, ipkg, snmp, mrtg, moc Service enabledssh, samba, itunes server, ftp NAS GPL source code can be download from

+ File system trace Auspex File System Traces [1] -timestamp- -type- -action- FID: -fid- OFF: -offset- SIZE: -size- HOST: -host- 1992, too old Other trace toolkits LTTng [2] SystemTap [3] Dtrace [4]

+ SystemTap script Trace Time Spent in Read and Write for Files Obtained from We’ll modify this script to watches each open, close, read, and write system calls on the system

+ Storage Virtualization [5][6] Provides a logical, abstracted view of physical storage devices Provides a way for many users or applications to access storage without being concerned with where or how that storage is physically located or managed Enables the physical storage in an environment to be shared across multiple application servers, and physical devices behind the virtualization layer to be viewed and managed as if they were one large storage pool with no physical boundaries.

+ Venders of Storage Virtualization Software based Datacore EMC FalconStor Gresham Enterprise Storage Microsoft Hardware based EMC HP IBM NetApp StoreAge Sun HDS

+ Product specification It often concerns about property in the following table An overview article can be visited on [7] (2006)[7] Maximum Capacity Drive/Storage Support Maximum Transactions CostMaximum Throughput Largest Virtual Volume I/O CachingSecurity Features Implementatio n Reporting and Logging Maximum Disks Maximum Virtual Volumes Provisioning Support Snapshot Support Services Supported

+ Implementation approach Host-based Using a software layer above the physical device driver intercepts the I/O requests performing the meta-data lookup and I/O redirection. LVM in Linux, LDM in windows Storage device-based A primary storage controller provides the virtualization services and allows the direct attachment of other storage controllers. Network-based When talking about Storage virtualization it is most commonly thought of as a network based device using fiber channel networks connected as a SAN The virtualization device sits in the SAN and provides the layer of abstraction between the hosts performing the I/O and the storage controllers providing the storage capacity.

+ In-band vs. out-of-band (network- based) In-band Symmetric virtualization devices actually sit in the data path between host and storage. All I/O requests and their data pass through the device. Out-of-band Asymmetric virtualization devices, sometimes called meta-data servers. These devices only perform the meta-data mapping functions.

+ Linux LVM [8]

+ Linux VFS

+ To Do List Collect file system trace with LTTng and systemtap, determine which is better. Reading book “Storage Virtualization: Technologies for Simplifying Data Storage and Management “ by Tom Clark, Addison Wesley, 2005“Storage Virtualization: Technologies for Simplifying Data Storage and Management “ Study some white papers from website bellow Virtualization.html Virtualization.html

+ Reference [1] [2] [3] [4] [5] [6] [7] html html [8]