Raid how does it work

Your question is answered in last 2 sentences of my article. My goal was also to make the explanation really easy and short. It is not so important if you want just understand how parity calculation works. You will just have the data without parity. So, your RAID array is in the degraded mode — as next disk fail will cost data loss.

After replacing the drive, the rebuild task will re-create the parity based on the data. Once the parity is re-created, your RAID array status switches from degraded to normal. And now, the array is ready to tolerate the next disk fail and does not lose all the data. Hello John! Your way of describing everything in this article is actually fastidious, every one can without difficulty understand it, Thanks a lot.

This was way more clear than anything else on the internet. Thank you. As someone who is still learning about how RAID works, this explanation made it very clear. Thank you! I agree to Open-E's terms and conditions and privacy policy. How does RAID 5 work? The Shortest and Easiest explanation ever! RAID 5 — how it works? Related Posts. We hope it shows… Read More. RAID 5: How does it work? The Shortest and… Read More.

RichardS September 03, 09 Good catch! Lukas September 06, 09 This is realy easy! Thanks for this. VA:F [1. Alaa S. I hope this helps. Austin Data October 12, 10 this is short!

VA:D [1. Rating: -1 from 5 votes. Jack February 21, 02 Very good explain. Thanks If my 2 disks are failed at a time, out of 7 disks, is it possible to get the data in raid 5.

Thanks in advanced. Rating: 0 from 2 votes. Mike March 07, 03 No, the data is unrecoverable. Rating: -1 from 1 vote. RAID Supported for all disks.

Data might become damaged or destroyed without harm to the disk or disks on which it is stored. For example, part of the data might be overwritten by a system malfunction; a file might be damaged or deleted by a user error or malice, and not noticed for days or weeks; and, of course, the entire array is at risk of physical damage.

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RAID 0 striped disks distributes data across several disks in a way that gives improved speed and no lost capacity, but all data on all disks is lost if any one disk fails. Although such an array has no actual redundancy, it is customary to call it RAID 0. RAID 1 mirrored disks duplicates data across two disks in the array, providing full redundancy. Two disks each store exactly the same data, at the same time, and at all times. Data is not lost as long as one disk survives.

Total capacity of the array equals the capacity of the smallest disk in the array. At any given instant, the contents of both disks in the array are identical. RAID 1 arrays mirror de data of one drive to another drive. So when your computer writes data to the array, the controller will actually write the data twice: to disk 1 and to disk 2.

PRO : Increased reliability since data is always saved in duplicate on two different drives. If one drive dies, the other will still be able to provide you the data. CON : Not very efficient when it comes to remaining storage , as you need at least two the same drives, but in the end only have the storage space of only one drive. RAID 2 uses striping on bit level, which theoretical could come with very high transfer rates speed.

However, at this point there are no commercial applications available that utilize RAID 2. Minimum number of required drives : 3 drives. PRO : Possibly very high transfer speeds. Think of it as data being written as follows: block 1 goes to drive 1, block 2 to drive 2, block 3 to drive 3 and a calculated parity to drive 4.

PRO : Data reliability is good. RAID 5 works in essence the same as RAID 4 block level , but instead of storing all the parity blocks on one drive, the parity blocks are evenly spread out over all drives. PRO : Very good data reliability and good performance. It actually maintains 2 parity calculations, and like RAID 5 these are equally distributed offering the ability to even recover from 2 failing drives. PRO : Good speed performance, and higher reliability. RAID 6 — Striping with double distributed parity.

These variations can offer additional speed and reliability but typically at the expensive of storage space. However these variations are typically not used in regular home settings. You can configure your own fitting your own needs. With JBOD, basically hard-disks are stringed in a sequence, offering the sum of the capacities of all hard-disks in the string.

There is no speed gain here, and when a drive fails in a JBOD the not all data is lost, only the data on the defective drive. PRO : Simple and Cheap way of bundling different sized disks. CON : No increase in speed or reliability. Your support is very much appreciated, and can be as easy as sharing a link to my website with others, or on social media. Support can also be done by sponsoring me, and even that can be free e.

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