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RAID Configurations Defined
RAID is thus far one of the most popular and effective corporate data solutions available to small business today. The cost effectiveness, safety and speed provided by RAID systems has yet to come close to that of other data storage solutions such as SAN and Snap Servers. There are varying configurations of RAID systems overall, but some of the key configurations include:
RAID 0 – The Striped Array
The RAID 0, while not a redundancy focused RAID solution, enables the user to create a high-performance data solution without a high-performance price.
On a RAID 0 system, blocks of data are retrieved from all disks on an alternative selection basis, which creates extremely efficient data writing and access. Finding and retrieving data on multiple disks increases the probability of quick access, making the meta disk in a RAID 0 somewhat superior to that of a single hard disk.
RAID 0 is an optimized hard drive performance configuration, creating disk space and disk input/output efficiencies, but without the redundancy safety provided by other RAID configurations.
The RAID 0 system works by writing data on alternate blocks on alternate drives, each using a defined stripe size. The advantages of this configuration include not only high speed data access, but full disk space use on both drives.
Recovering the RAID 0 system is frequently not for the non-professional. All drives in a RAID 0 system must be accessible for a recovery to occur, and Hard Drive Recovery Group has the equipment available for this job.
RAID Configuration Data Recovery Descriptions
RAID 1 – The Mirrored Array
With a RAID 1 array, data security is paramount. So while RAID 0 is highly concentrated on performance, the RAID 1 system skips this, instead ensuring that data blocks are duplicated on all drives within the array. The read performance in a RAID 1 is often similar to that of a RAID 0, while the actual writing performance is typically heavily degraded (although still frequently better than a single drive solution).
Data blocks can be multi-tasked, meaning 10 data blocks can be read at once, one per hard drive, per time. This particular configuration does not allow for extra storage capacity, obviously, as duplication is its main consideration.
Typically, if one of the drives in a RAID 1 setup fails, the other will take its place, with the user being warned by the server software. Often, Utility programs are recommended to remedy the situation.
Where Utilities can fail include:
Corrupt Mirrors – If bad data is on the weak drive, it may be transferred to the strong drive through mirroring. This can cause havoc with the system.
Broken Mirrors – If your RAID configuration mirror breaks, your system may try to boot, but will often fail. This is the result of the mirror meta data already put in place.
Incorrect Mirroring – Some utilities will by default rebuild incorrectly, and point to the wrong drives.
RAID 4 – The (Imperfect) Perfect Balance
The advantages of RAID 4 basically can be summed up as equivalent to both that of the RAID 0 and 1 systems. Data organization shares the characteristics of both those configurations. Technically, the physical block one to N-1 (where N is the total block number) are striped as per RAID 0, while the Nth data block stores the parity of each bit in the first striped blocks. This solution is fantastic on a recovery basis, as it uses the parity information of the N block in order to recover data in the event of single drive failure.
This is a high efficiency solution, with similar to RAID 0 read speeds, and better than RAID 1 write speeds. Restoring failed drives with a RAID 4 is far easier than with a RAID 0, as the Parity disk becomes an in-built data recovery tool.
RAID 5 – The Ultimate RAID Solution?
The RAID 5 solution takes the best of all worlds. The key difference is that it takes the data from RAID 4’s parity disk and spreads it over several hard drives, thus negating the need for a specific parity hard disk. This system reduces the load, and thus the wear on the parity specific drive (because technically, it is spread out and now non-existent), and increases performance in the meantime.
RAID 5 combines the advantages of RAID 0 and 1 by using striping, and by breaking these strips into blocks. Each stripe in a RAID 5 array is not a data block per say, as it is a parity block. Typically, these systems can survive the loss of one drive. But two drives lost in a RAID 5 system typically kill the array.
Professional Help Is Here
These are the main causes of RAID 5 failure that require data recovery. But there are others. Remember that at Hard Drive Recovery Group, a consultation is always free. Don’t take chances when it comes to your mission critical RAID-stored data. Call us first.
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