Raid dp pdf

If you have 4 separate raid 5 arrays, would a hard drive failure in one of the arrays affect only the performance of the one array and the others would remain unaffected? Can anyone explain this? You have a file that is broken into 10 chunks, and those chunks must load into memory before you can use them. So on one dish, your hard drive controller loads block 1, then block 2, then block 3… etc.

In raid 0, it would load block 1 and 2 at the same time, then block 3 and 4. But if you lose a disk, you only have half your file. What you are recommending will not increase speeds by much, unless you are loading to files in separate folders. Thanks for beautifully explaining the types of RAID. I am a tech guy and was using RAID 5. Somehow, I had lost the data from it. So, I asked the solution from my colleague and he advised me to use Stellar Phoenix raid recovery software. This works great for me.

Stellar Phoenix is a scam company and this fake comment is just sock puppet marketing. Buyer Beware. Great post! When backing up data I always use the style strategy. But, more is always better. You opt for Dual mirror: so in that case, no need another drive for TM? If TM, then the drive is also need 3TB?

You can put other data on that partition but it apparently more common to use a separate partition. The mirrored drives protect your data against 1 disk failing. Accidental errors like incorrectly deleting a file or misplacing it or data corruption are more common and a bigger worry.

That is why you use Time Machine for the data residing on the internal drive but of course the same also applies to the data that will be stored on those mirrored drives.

So in my opinion, the ideal setup is that the third drive on which you put your Time Machine data is also a 3GB drive, split into one partition for Time Machine and a second bigger partition on which you occasionally copy the main data stored on your mirrored drives.

I know that adds to the cost but I like having a spare copy of data and I like having systems with disks that are all the same size. Easier to resell afterwards, easier to repurpose as a 3-disk RAID set if your storage needs change over time. Also if I would like to use this ext for Time machine, do I need to partition as well? As have3 HD 3TB for data? I would personally opt for dual mirrored 3TB drives instead of 4x 1 TB.

It is simpler, offers better performance, makes less noise and uses less power. When you add a third disk for Time Machine you can still do it all with a 4-disk enclosure, instead of having to buy a more expensive 5-drive system. With 3 disks in use, you still hafe a spare slot if you want to expand storage in the future. If you go for a NAS box its software takes care of making those mirrored drives appear as one partition.

Check out YouTube videos on setting up a Synology, Qnap,… system — it is pretty straightforward. One question. If we take RAID 5, what is pairity checksum features. If we have 4 disk and configured raid It will do stripping means fast data flow as data being distributed but what is pairity for?

The parity is used for recovering data in case of drive failure. With RAID6 two disks can die simultaneously. More detailed descriptions of the way parity works can be found elsewhere on the web. This page is meant to give a general overview. Having an extra offsite disk is a good idea. In many NAS enclosures it is a bit of a hassle to swap drives.

Once something is clunky, you stop doing it after a while. Why not use a separate harddisk docking station for the off-site copy? I am looking to install an external multiple bay NAS drive for home use. Approximately TB, keeping in mind performance and that I will be backing up all data on an external HDD stored in my safe. What would be the best RAID configuration to use? Thank You for any insight and information. What an excellent explanation of RAID…..

Thank you so much. Hi, I have read your explanations about RAID configuration and it is very much informative with pictures. If I understand your first question correctly, you are wondering if you can use a smaller drive for parity compared to the other drives in the RAID set. The hardware or software RAID controller determines if you can mix different sizes and types of drives.

Many require all drives to have the same capacity. Alternatively they use the capacity of the smallest drive across all of them.

Please note that it is 6 gigabit per second, not 6 gigabyte per second. There is some overhead which means the fastest real transfer speed is around megabyte per second.

A hard disk cannot reach that maximum speed, only SSDs are capable of doing that. You should also keep in mind that if you copy files from one logical drive to another on the same HDD, your computer is reading from and writing to the same drive simultaneously. That also slows down the data transfer. To take advantage of Sata 3 speeds, you need both a Sata 3 drive and a Sata 3 controller.

Also as noted, the 6 gigabit-per-second transfer rate specified for Sata 3 is only what the controller is capable of. A Sata 3 hard disk will never achieve a full 6Gb per second transfer rate, but it will be way faster than a Sata 2 drive. SSDs will get you much closer than any hard drive, but no storage media will actually ever reach the maximum transfer rate of the controller. The type of data being transferred is a significant factor in this as well. Also the 6Gb per second Sata 3 transfer rate only applies to sequential reads, which are faster than random reads, particularly on rotating media.

Write operations are much slower, as the media itself is the bottleneck. Can you please tell me what is the maximum size for one virtual disk under RAID 1. What is the largest disk size it supports? I have a Gb and a gb drives If i RAID 0 with them will I get gb of space under one drive or will it be limit to gb being to lowest size of the two?

The storage space added to the array by each disk is limited to the size of the smallest one, which means this would be very unefficient. If your smallest drive is GB, then a raid 0 configuration would give you twice that amount, or GB.

You can certainly do this. I would just get a second large disk though. HDDs are moving back to being cheap again. Set aside the smaller disk for a backup drive and sync some important folders to it.

The other disadvantage is that you cannot go back in time and recover a file you accidentally deleted two days ago. Previous Versions. I personally have two external disk enclosures and alternate back-ups of all data on these enclosures. One of them is stored at my parents house and during each visit I swap them out so I always have an off-site backup. There are two disadvantages of just mirroring your data on additional internal disks: your backup is physically in the same location so if the PC gets stolen or there is a fire everything is gone.

If you attach a separate box containing two or more drives to a computer and those drives are running in a RAID configuration, there is a circuit board in that box that handles the distribution of the data across the drives.

That board has its own CPU: it is effectively a mini computer but it typically is called a hardware controller. Most of it is in an alternate location 3tb and that is also spent so another external drive without a backup is being used.

I am wondering if a mirrored 12 or 16 gb raid 1 drive is a good idea my current 4tb can be moved to the other locale giving me 7tb. I anticipate using at least 1TB in the next year and possibly more. If I understand it correctly you currently have around 6 TB of data and you expect to add at least 1 TB each year. I am not familiar with the brands you mention. Have a look at Drobo as well — their RAID boxes seem to be pretty popular but there are dozens of alternatives on the market.

I would stay away from RAID with such a setup. RAID works best for drives with the same capacity and using the same type of controller. If you want higher throughput remove the big drives from their external enclosure and put them internally on SATA 6. That is faster than most USB3 controllers. Is it possible you can explain to me how to do the following or direct me to a tutorial? On the other hand, I have lost many hard drives and all the information from crashes.

Mounting drives on Windows 7 is explained on this Microsoft page. I cannot give you a short and relevant description of how to do this, especially not without any knowledge of your setup. Once that is done, the RAID volume can be partionned and formatted from within the operating system. That depends on your definition of important. For company servers, RAID 6 is probably the way to go right now. Hi, just want to check if i understand.

So for example.. A storage box consists of an array of 6 disks, 1 TB each and the effective storage capacity, based on the RAID level used is.

The way you have explained using simple terms I really liked it. But what I feel is you should have included RAID 6 as it can withstand failure of more than one disk. Its interesting to learn something that is quite different from that of others. There are lots of heated discussions about that on the web.

If you run benchmark software to measure the performance of striped SSD drives, there is a significant speed increase. Wikipedia is clearer! Fixed — Fine nuances like that are difficult to grasp for me since English is not my native language. Normal procedure is to use raid4 to resync and then revert back to raid0. From everything I am seeing on comparisons between both, if you only have 4 disks, the fault tolerance and performance are the same.

My guess based on my mathematical intuition is that if you have a number of drives that is a power of 2 it will be the same. I need to deal with very large data set with typical file size of gb, hundreds of them, in a workstation.

Both read and write. Would Raid 3 be better than Raid10? Raid 5 only requires a minimum of 3 disks. As for file size, that is upto whatever file system you put on the volume created by you Raid array. I have used RAID 6 in one of my server.

This has allowed me to create two hot swap disks. I deceided to use it on case scenarios such as: if two active disks fail at the same time. Featured in a NEC server rack mount. I have head that the government is now doing work on RAID yes, negative This technology is based on tensors and promises to put all other RAID to shame.

Find a good disk calculator and you should be able to figure out the impact on your setup. Theoretically you could just stick one LUN on each disk group, but that likely would not be the best way to set it up. We're pretty small and don't have bid demands, so we just made a single RAID 10 from the 14 drives plus a hot spare and then created LUN's from there for the various machines that connect to it.

Instead of doing the parity calculation and write on every strip, it waits for multiple stripes and--again, according to them--write with performance equal to RAID10 but with the failover capability of RAID6. The last link I posted above actual explains it pretty well and seems to be pretty honest.

It's an interesting argument! I don't know, sounds like a lot of good old fashioned marketing speak to me. Holding writes in memory until you have enough to write an effecient block of data is an interesting idea and likely does have some performance benefit, but you still have to write the data sooner or later, you still need to calculate the parity bits but now there is overhead to calculate when to write the data , etc there is no way around it.

At the end of the day it may not make a difference regardless, all depends on how much performance is needed. I'm familiar with the MDi configuration. I was just intrigued about not having to worry about the RAID type because the appliance "has it all figured out". It really sucks how these things are so damn expensive and take so much work to configure, that no one can do benchmarks for them like they do with graphics cards and motherboards on the consumer level.

Maybe that needs to be a new Spiceworks feature: The Benchmark Club. There has to be a few of us here with similar setups and we can run benches in our environment and compare them and write reviews based on this.

In the Enterprise world, you really have to take the vendor's word for it. And, if it is waiting for multiple writes, there is obvious risk there with lots of data residing in memory rather than on disk. Unless I read the spec's wrong? That is totally correct. It seems it would be more accessible to a reader on the level that needs these explained. If storage requirement is of 10 TB. What will be actual required storage in both category.

Applicastion is for Video Storage. The differences are purely academic :. This is an awesome explanation, thank you so very very much. I really now feel very comfortable with understanding RAID. What RAID would a server usually have? Thanks alottttttt….!!!! In raid 6, how are the parity bits calculated? Thanks a load for uploading.. Save my name, email, and website in this browser for the next time I comment.

Notify me of followup comments via e-mail. All rights reserved Terms of Service. RAID 2 This uses bit level striping.

In the above diagram b1, b2, b3 are bits. E1, E2, E3 are error correction codes. You need two groups of disks. One group of disks are used to write the data, another group is used to write the error correction codes.

This uses Hamming error correction code ECC , and stores this information in the redundancy disks. When data is written to the disks, it calculates the ECC code for the data on the fly, and stripes the data bits to the data-disks, and writes the ECC code to the redundancy disks. When data is read from the disks, it also reads the corresponding ECC code from the redundancy disks, and checks whether the data is consistent. If required, it makes appropriate corrections on the fly.

This uses lot of disks and can be configured in different disk configuration. This is expensive and implementing it in a RAID controller is complex, and ECC is redundant now-a-days, as the hard disk themselves can do this. RAID 3 This uses byte level striping. In the above diagram B1, B2, B3 are bytes.

Uses multiple data disks, and a dedicated disk to store parity.