Advanced Product Features for Janus2 RAID Units

These advanced functions are available on the following RAID models:

• Janus6652E 16 Bay SAS/SATA II-SAS RAID
• Janus6651E 16 Bay SAS/SATA II-4Gb Fibre RAID
• Janus8850 24 Bay SATA II-U320 SCSI RAID
• Janus4551 12 Bay SATA II-4Gb Fibre RAID

• Innovative New Array Structure: The JanusRAID2 series features a new innovative array structure that hierarchically organizes storage objects. With this structure, physical drives are combined into Disk Groups (DG). Disk Groups are subdivided into Logical Disks (LD) where arrays are created. Lastly, Logical Disk can be combined or striped together to form Volumes. Either volumes or LD can be pointed to a LUN which are then presented to the host computer.

• Online Expansion and Defragmentation of Disk Groups: New physical disks can be added by expansion of a Disk Group (DG) while the unit remains online. During the process of expanding Disk Groups, defragmentation can be selected to move unused capacity to the ending LBA of a Disk Group. Defragmentation can also be selected at anytime there is unused storage space residing between Logical Disks.

• Online Expansion and Shrinking of Logical Disks Logical Disk (LD): Online Expansion can increase the capacity of an online LUN, instead of having to create a separate partition for unused capacity or capacity gained from Disk Group Expansion; now your storage can dynamically grow as your demands grow. In the event of overestimating requirements for Logical Disk capacity, shrinking can be used reduce the allocated storage of a Logical Disk.

• Read & Write Performance Optimization: With ongoing research in performance optimization an adaptive pre-read algorithm has been developed that is able to track and recognize IO behaviors that will adjust controller cache accordingly. Pre-read depth and multipliers are adjustable to enable fine tuning for your specific application. Write cache has several options; including cache flush period, write merging, and sorting, that are also user configurable to further fine tune performance.

• Array Recovery Utility: The JanusRAID2 series now provides an Array Recovery Utility (ARU) that can aid a user in the event of multiple drive failures corrupting the RAID array of a Logical Disk and/or volumes. The ARU enables users to recover lost disk members of a Disk Group, and will automatically recover Logical Disks and Volumes.
• Array Roaming Utility: The Array Roaming Utility gives users the ability to easily migrate drives between slots or RAID subsystems. This user friendly utility is built into the GUI of the JanusRAID2 to simplify storage management.

• Performance Monitoring: A performance monitoring utility has been designed to the needs of our users. Hard disk drives, controller cache, LUNs, and host ports can be monitored concurrently with extensive detail. These statistics allow users to view current average, accumulated, maximum and minimum of the aforementioned items.

• Event Monitoring: Event logging has been improved with many new features and functions that are now available in the JanusRAID2 series. Event logs are now categorized based on their severity level and type. Entire logs are stored in non-volatile memory to prevent lost information after power has been lost or removed. Another new function is the ability to download the logs in a user readable format which can be sent to technical support for easy analysis. A system administrator can be notified of events, based on severity level, by configuring redundant email servers, or multiple SNMP servers.
• Task Management: With the aid of an onboard Real Time Clock (RTC) that is sync-able with an NTP server. Tasks can be scheduled to run once or periodically during off peak hours to prevent the least amount of impact on the JanusRAID2 storage subsystem. Progress of the tasks is easily viewed from the GUI interface and can be stopped manually at anytime.

• Selective Initialization: There are three initialization methods supported: Regular, Background, and No Initialization; and two initialization modes: Parallel and Sequential. Regular Initialization will initialize the array, but not allow host access until the initialization process has been completed. Background Initialization will begin the initialization function, but will run in the background, allowing an array to be available for access immediately. No Initialization will bypass the initialization function, and bring an array online instantly. When initializing an array in Parallel mode, multiple arrays will be initialized together simultaneously, while in Sequential mode, arrays will be initialized in a user specified order.
• Selective Rebuilding: The standard rebuilding mode used is Parallel, where multiple arrays are rebuilt at the same time. However the JanusRAID2 supports a new mode, sequential and prioritized. In sequential mode a specific array, such as a mission critical array can be given more resources to enable a quicker rebuild thus decrease time in degraded mode.

• PathGuard MPIO: PathGuard MPIO software uses redundant physical paths to create a logical path to a storage subsystem to enables greater performance and reliability. PathGuard supports four different options: Read/Write I/Os, Read/Write Bytes, Command Queue, and Round Robin.

• Global or local spare disk: With the new JanusRAID2 storage structure, local and global spares can be configured. Local spares will belong to specific Disk Groups and will only replace faulty drives in a specific Disk Group. Meanwhile, Global Spares will replace faulty disk in any available Disk Group.

• Regenerate Parity: A simplified feature of Disk Scrubbing (DS), Regenerate Parity will regenerate the parity of a Logical Disk(s) in a Disk Group without a parity check.

• Dual Flash ROM: Dual Flash ROM per controller gives higher RAID system availability and reliability during firmware upgrading or in the event of a single ROM failure.

• Web-based GUI: Embedded CGI-based GUI (graphic user interface) management interface can be accessed through a web browser. The GUI allows users to easily setup RAID arrays, lun mapping, etc. and also provides remote monitoring of drive health, fan, and power supplies.

• Disk Self Test (DST): Before the release of this function, users of RAID systems were forced to test suspected bad hard drives in a host computer individually using a drive manufacturer’s utility. This function tests the health of hard drives with them installed in the RAID unit. DST performs write tests, servo analysis, and read scan tests; the test results are then displayed on the LCD and hyper terminal output. This can aid the user in deciding whether or not to replace a suspected failing hard drive. We highly recommend running this test before initializing a RAID set to ensure a healthy RAID solution.

• Disk Scrubbing (DS): With today’s RAID subsystems being capable of storing multiple terabytes, it is becoming increasingly difficult to manage and maintain that large amount of data. To aid a user in maintaining their data’s health, The Janus2 RAID line has a Disk Scrubbing firmware function. The data and/or parity stored on hard drives can sometimes become corrupted; this data can also reside in areas that are not accessed for long periods of time. DS uses idle time to test the disks, and if a sector is found to be corrupted, the data will be regenerated from other RAID member disks and will be written to an uncorrupted sector. The purpose of DS is to prevent the possibility of having multiple corrupted sectors in a single stripe, which is one of the main causes of data loss.

• Disk Clone (DC): Hard drives are the most likely component to fail in a RAID array, and it's almost impossible to predict when the failure will occur. When a failure does occur, the RAID unit will have to regenerate data from the non-failed hard drives to rebuild a new drive, and the RAID array will be in degraded mode. A unit in degraded mode is vulnerable, because if a second hard drive fails the RAID is destroyed and data is lost. Disc Clone solves this problem. With the help of the hard drives built in S.M.A.R.T. function, DC can determine when to begin cloning a bad drive to a hot spare. Upon completion of cloning, the new cloned disk can take the position of the failing disk or can stand-by until the original disk fails, then take the failed disk's position. Disk cloning is used to prevent a rebuild from ever occurring and having the unit operating in degraded mode. 

• Support for greater than 2TB LUN: Two firmware options are available to surpass the 2 terabyte limitation; 16byte CDB and variable sector size. With either of these functions enabled, users are able to create slices and map LUNs greater than 2TB to their respective host channels.



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• Background Initialization: Initialization occurs during creation of a RAID array by zeroing out / formatting drives. By default the initialization process occurs with the unit offline, and inaccessible. With background initialization, the RAID array can be accessed during the initialization process so that the unit can be setup without having to wait several hours to complete initialization.

• BBU: An optional BBU can be included in the RAID system to ensure data integrity in the event of a power outage. The BBU, or battery backup unit, will provide power to the on-board cache of the RAID controller in the event of a power outage. This will allow any data that is still stored on the cache to be saved until power is restored. Once power is restored, the RAID controller will flush the cache to drives.