EMC Storage Product Knowledge Sharing

The following rules and recommendations CX systems:1) You cannot use any of the disks 000 through 004 (enclosure 0, loop 0, disks 0-4) as a hot spare in a CX-Series system.2) The hardware reserves several gigabytes on each of disks 000 through 004 for the cache vault and internal tables. To conserve disk space, you should avoid binding any other disk into a RAID Group that includes any of these disks. Any disk you include in a RAID Group with a cache disk 000-004 is bound to match the lower unreserved capacity, resulting in...

LUN to bind Restrictions and recommendations ----------- Any LUN You can bind only unbound disk modules. All disk modules in a must have the same capacity to fully use the modules' storage space. --- In AX-series storage systems, binding disks into LUNs is not supported. RAID 5 - You must bind a minimum of three and no more than sixteen disk modules. We recommend you bind five modules for more efficient use of disk space. In a storage system with SCSI disks, you should use modules...

RAID 6 Protection RAID 6 was implemented to provide superior data protection, tolerating up to two drive failures in the same RAID group. Other RAID protection schemes, such as mirroring (RAID 1), RAID S, and RAID 5, protect a system from a single drive failure in a RAID group.RAID 6 provides this extra level of protection while keeping the same dollar cost per megabyte of usable storage as RAID 5 configurations. Although two parity drives are required for RAID 6, the same ratio of data to parity drives is consistent. For example,...

As we know that we have different type of RAID but all the raid type are not suitable for the all application. We select raid type depending on the application and IO load/Usages. Actually there are so many factor involved before you select suitable raid type for any application. I am trying to give brief idea in order to select best raid type for any application. You can select raid type depending on your environment.When to Use RAID 5RAID 5 is favored for messaging, data mining, medium-performance media serving, and RDBMS...

A RAID is a redundant array of independent disks (originally redundant array of inexpensive disks). RAID is a way of storing the same data in different places (thus, redundantly) on multiple hard disks. By placing data on multiple disks, I/O (input/output) operations can overlap in a balanced way, which improves performance. Since multiple disks increases the mean time between failures (MTBF), storing data redundantly also increases fault tolerance.A RAID appears to the operating system as a single logical hard disk. RAID employs...

LUN Basics Simply stated, a LUN is a logical entity that converts raw physical disk space into logical storage space that a host server's operating system can access and use. Any computer user recognizes the logical drive letter that has been carved out of their disk drive. For example, a computer may boot from the C: drive and access file data from a different D: drive. LUNs do the same basic job. "LUNs differentiate between different chunks of disk space. "A LUN is part of the address of the storage that you're presenting...

Very simply, RAID striping is a means of improving the performance of large storage systems. For most normal PCs or laptops, files are stored in their entirety on a single disk drive, so a file must be read from start to finish and passed to the host system. With large storage arrays, disks are often organized into RAID groups that can enhance performance and protect data against disk failures. Striping is actually RAID-0; a technique that breaks up a file and interleaves its contents across all of the disks in the RAID group....