Thank you very much Asher, I now understand RAID fully. Tow days left to my exam and finally I have found a very valuable tutorial to help me with my study. God blessing.
This is the most thorough explanation of RAID by clearly a professional. Look no further. I'm personally now looking into SSD NAS, anyone have any reviews on it, would be appreciated
For a long time, we were told by I.T. senior engineers to create a big RAID5 array, and then create two partitions, one for OS and one for DATA (including databases). The redundancy of the RAID5 was "sufficient" for many production environments. That has now changed, and for production environments, we have seen RAID1 for OS two drives and RAID10 (6x drives) for DATA and databases. It provides the fastest, most reliable, and highest redundancy on the server itself. Two drives can fail, on the RAID10, different mirrors though, and the server will continue to function. If the server is from the newer ones, and you can add 1x hot spare, even better. I have two companies with multiple servers running these configurations I did, and seven years strong with the occasional HD replacements of course, but the servers functional.
Great Explanation.....I don't understand why people are focusing on raid(s) that are not common in the industry. The basics are well explained here....I was surfing and stumbled upon this. Many people will appreciate this, and the format of its presentation.
i have read a lot about raid and saw videos, and i only understood it when i saw THIS video. Wish all my teachers were like this guy... THANK U SO MUCH!!!
With one hour of my time I went from knowing next to knowing to having a great base of knowledge on several types. Thanks for posting this video. Just had a hard drive failure and although I have two external HDDs I am never proactive at making backups. I think RAID 10 is the way to go for me. Storage space is cheap.
I've never been informed about RAID before, I'm drunk and playing WoW in a raid while listening to this talk. And now I know how RAID's work. I call that effective teaching! Well done.
Saw it today ( wishing to have seen it earlier ) - best contents ( business need, fundamentals, design aspect, environmental aspects, commercial aspects, practical knowledge, use cases ) with completeness and flawless delivery ( Smart Screen helped great )
wow best lecture on raid ever didn't mention the least amount of drives needed for raid 6 but other than that was excellent. If someone knows for fact pls address this. thanks for the free lecture
Thank you for explaining the details on why RAID 0 writes so quickly. Other sources did not break it down to explain that if it takes 1 second to write 1 MB, that it would only take 1/2 second to write the 1MB if there were 2 discs in array and the 1MB was divided into two blocks.
Very good superb video and very much elaborate about RAIDS levels . I was got 80% idea about RAID levels by watching this video.thanks very much for sharing valuable information with us.
now i had a full idea why some of my old data become unreadable, and in the first place i did not see the deference between RAID 5 & 6 and you make it very clear thank you very much RAID 6 is the best in my opinion until now, and i will keep looking. after all that can the user use same two drive specification with two different brands or there will be a problem with read write performance
With Software Defined Storage, the concept of hardware RAID is emulated at the driver and CPU level. ZFS, Ceph and Gluster are product families utilizing scalable storage. They generally have less performance (unless using SSDs for Cache and or RAM or nVME), but they scale very well and offer much more robust file integrity options.
Thank you very much. This is an excellent video. I am currently trying to recover important data from a failed RAID 5. After loosing a drive the entire RAID system failed. I still got 3 X 2TB drive saying good. What software can I use to access my data and copy them before I re create a new RAID. I need a prompt response because I need make decisions immediately as I am working on this currently. Thanks once more for the fantastic video.
at 34.52, I think Dear Mr. Asher you had mad a mistake, which is when you wrote 100 GB Disk capacity will lost. the correct is 50GB, because when you give the example of 4 disks each has 2TB, the answer was from your student was 2TB same as your example was. I hope you get me dear. Thank you too much for you.
J Martinez, wow, thank you so much!!! I'm here wrapping my head around NetApp's RAID-DP, and you made it very clear!!! I think the only difference between RAID-6 and NetApp's RAID-DP, is that they use not one, but two dedicated parity disks. There's no striping of parity. I suppose that makes for even better performance? But, I wonder if rebuild is even slower? Thank you again!!!
Hi Martinez, Best and simple explanation.Thanks for producing such a tutorial. I have a small concern as below When you are explaining RAID 5 - Parity at 28:25 th minute, you are stating as "It compresses the data and stripes across all the hard drives" I don't agree - it should be "it compresses the data and the parity is distributed across the hard drives. if the party also stripped we will have the disadvantage same as raid0 which simply there is no - fault tolerance for the parity. ( Simply Stripped data blocks with Distributed Parity)
RAID1: Depending on your RAID controller, RAID1 may have Striping on Reads, but never on Writes. There will be a performance increase on reads (the longer the read, the better the performance may get). Writes are nearly the same as a single drive, but since the drive has to do a "copy on write" the RAID1 array has to confirm two writes (at roughly the same time)... Latency (not speed) on Writes in RAID1 goes up slightly.
hello Mr J.Martinez, I have been watching your video and it is very informative and I learn a lot from your lectures I just wanna ask about the raid 5 configuration. let us say you have 3 physical hard drives and each has a capacity of 2TB so your actual total would be 6TB, may question is if you set up in raid5 do you loose 2TB which is 1pc actual Harddrive or you will loose only 1TB? what will be the data storage amount will you loose?
Excellent! not many videos like this out there, this is how really things are explained. Thank you so much guys!! liking it and sharing it as well. ^.^
The RAID 5 Parity bit isn't "compressed" the way you describe. The RAID controller knows how many drives are in the RAID, then it counts the 1s for each block level. If there's an odd number of 1's the parity bit for that block level gets set to 1, if there's an even number of 1's the parity bit gets set to 0. If any single drive fails, you can reconstruct what the missing bit was by counting the number of 1's at each block level from the remaining drives and then figuring out whether it was a 1 or a 0 based on what the parity bit says it should be. There are more nuances to this explanation, but it doesn't use dictionary compression the way you explain... that would be far too slow and take up too much memory at this low-level of operation.
Yes, he's a bit flawed. This is what I think about his genius HDD buying guide: "Just because one hard drive sat on a shelf a bit longer than the other and at an other location( but from the same factory with the same specs), doesn't mean, that I's gonna fail sooner. To me, the lifetime of both starts, when they actually start using them (read and write), not at the time of manufacture. In case of new drives of course. Going with different brands (and manufacturing procedures), but the same specs would make more sense to me."
9:10 You said having 10 hard disk drives is 90% of chance of losing all the data. However, if the pieces of information (chunks) will be divided by ten on each drive, doesn't that mean that the more drives you have the less read-write process each drive will have? If so, then can we say that the less drives we have, the more chances of fault we're gonna end up having because all the read-write processes will be focused on fewer drives? Just a thought I have.
Awesome explanation! I have a situation where I have six drives in a raid 5 and lost two drives. Can you recommend any data-recovery software that might help me salvage my data?
I want to thank you very much for this video! I don't think I could have asked for a better explanation considering I got to practically sit in a classroom. I do have one question - I do not understand how with RAID 5 or 6 the amount of backup storage requirements does not go up with an increase in data. How can one hard drive size (with RAID 5) out of 8 hard drives backup everything in a hard drive failure? If each hard drive was 1 TB, why would there only be 1 TB needed for space whether it is out of 4 or 8 hard drives of the same size?
Masterr59 Parity is not exactly compression and it can't rebuild the other data alone. It uses the data of the other drives to calculate the missing info. Here's an example: Let's say a parity of 1 is stored for an odd sum and a parity of 0 for even. Striped on seven drives is 1 0 1 1 0 1 1. Since the sum is odd, 1 is stored in parity. So with one drive not working: 1 0 1 * 0 1 1, the parity of 1 says the sum is odd so the missing value must be a 1. Does not exactly work this way, but explains how parity works. It does not increase the more drives you add, but relies on the data on the other drives. Also explains why more than one drive failure makes a single parity of RAID 5 ineffective.
How fast is RAID 5 compared to RAID 1? The video says it's faster, but my cousin said he did raid 5 and it was really slow (so slow that he had to switch to RAID 1).. Do you need a RAID card for the speed? Could it have been bad software or setup?
This was by far the most understandable and comprehensive explanation of RAID that I have ever seen. Great job!!!
REALLY . Its a nice video that make me clear about RAID after 9 years.
Mr. Martiznez, this is the best explanation of RAID that I have ever come across. The lecture was much appreciated.
I concur. Very well done.
Awesome mr Martiznez BRAVO
I never understood the RAID that well before watching this. Thanks for detailed info. Keep sharing knowledge.
It is a complex yet simple matter.
And important to know what to choose when you set up your RAID levels.
I am speechless.
Dear respected tutor your awesome...
the BEST for RAID that you can found
Thank you very much Asher, I now understand RAID fully. Tow days left to my exam and finally I have found a very valuable tutorial to help me with my study. God blessing.
Man , this is like the best NUMBER 1 class about raid , watch it!
This is the best video on YT about RAID. Thanks
This is the most thorough explanation of RAID by clearly a professional. Look no further.
I'm personally now looking into SSD NAS, anyone have any reviews on it, would be appreciated
Great explanation. Like someone else stated before, if you don't understand what RAID is with this, you never will. Congratz to Mr. Martinez.
For a long time, we were told by I.T. senior engineers to create a big RAID5 array, and then create two partitions, one for OS and one for DATA (including databases). The redundancy of the RAID5 was "sufficient" for many production environments.
That has now changed, and for production environments, we have seen RAID1 for OS two drives and RAID10 (6x drives) for DATA and databases. It provides the fastest, most reliable, and highest redundancy on the server itself. Two drives can fail, on the RAID10, different mirrors though, and the server will continue to function. If the server is from the newer ones, and you can add 1x hot spare, even better. I have two companies with multiple servers running these configurations I did, and seven years strong with the occasional HD replacements of course, but the servers functional.
The best explanation of RAID, Thank You
Great Explanation.....I don't understand why people are focusing on raid(s) that are not common in the industry. The basics are well explained here....I was surfing and stumbled upon this. Many people will appreciate this, and the format of its presentation.
i have read a lot about raid and saw videos, and i only understood it when i saw THIS video. Wish all my teachers were like this guy... THANK U SO MUCH!!!
ts really wonderfull,everything is explained point to point was and too deeply.Please sir upload more videos on storage.For this a grand salute
This is the best video i have ever watched abouet RAID
Very good. Explained clearly and perfectly
I absolutely love the way he explains this so clearly. I checked the rest of the videos on the channel and was slightly disappointed.
Now this is how you explain RAID! Great work!
Glad to help!
With one hour of my time I went from knowing next to knowing to having a great base of knowledge on several types. Thanks for posting this video. Just had a hard drive failure and although I have two external HDDs I am never proactive at making backups. I think RAID 10 is the way to go for me. Storage space is cheap.
this guy is a real teacher....nice
I've never been informed about RAID before, I'm drunk and playing WoW in a raid while listening to this talk. And now I know how RAID's work. I call that effective teaching! Well done.
no pun intended ;)
BEST!!!! RAID Lecture!!!😀😇 well done J Martinez
You are the best teacher i ever had
I needed a refresher on RAID and this by far is the best. midway into lecture it all came backThank you
Are you still teachin'? because I knew about raid and still watched the whole topic. Well done man, wish you were my teacher
wow.. am so clear now. Hats off Mr.Kartinez.. very simply done
Very clear and detailed explanation of RAID
No body can explain better than this video, excellent explanation thank you :)
the bestest.... video i have ever watched on Raids lecture most useful was Raid 5 & 6 fully understood
Saw it today ( wishing to have seen it earlier ) - best contents ( business need, fundamentals, design aspect, environmental aspects, commercial aspects, practical knowledge, use cases ) with completeness and flawless delivery ( Smart Screen helped great )
Nice lecture, i feel i know more than i ever intended to know on this subject
During the rebuild the lost Disk, is D driver will still working on network very slowly, or it will be stopped till the rebuilding finished?
wow best lecture on raid ever didn't mention the least amount of drives needed for raid 6 but other than that was excellent. If someone knows for fact pls address this. thanks for the free lecture
Excellent Explanation I ever heard. Thank You
Glad it was helpful!
Excellent presentation; nicely explained, informative with a well understandable pace.
Hope to have some more from you on other topics.
Brilliant presentation / lecture.
great video i have learned a lot from this video thank you very much guys
Best RAID explanation.
Glad you think so!
Wonderful. Precisely what I wanted. One of the best tutorial if one want to understand RAID and its working! Thanks for video
Great explanation, very clear and easy to understand
Well simplify professor, thanks a lot for this lecture.
Thank you for explaining the details on why RAID 0 writes so quickly. Other sources did not break it down to explain that if it takes 1 second to write 1 MB, that it would only take 1/2 second to write the 1MB if there were 2 discs in array and the 1MB was divided into two blocks.
Excelent class and excelent domain of english. Congratulation
best lecture...all explained very clear. I wish I had this kind of teachers....BIG LIKE.
You are a great instructor. I wish I could go back to school.
Very well explained, I needed to go further in my knowledge in Raid especially the difference between 5 and 6 and you did it well.
GREAT!!! I learned a lot about RAID and it will help me to make a smart decision on which RAID to use for my work.
waaw guys, Straight on point...I have been failing to understand the RAID groups but now I have a clear picture. THANX A LOT!!!
Incredible explanation! Thanks so much for this clarity.
You're very welcome!
Very good superb video and very much elaborate about RAIDS levels .
I was got 80% idea about RAID levels by watching this video.thanks very much for sharing valuable information with us.
Very nice video and anybody can easily understand RAID through this video. Thanks for sharing such videos
Nice explanation sir...
Professional explanation of what was most confusing in my studying time. Tack you sir :)
What did you study to learn this stuff?
Networking
the explaination about raid 6 is wrong tho
Great explanation, I liked the real world examples that you gave based on your experience!!
The best educational video!
now i had a full idea why some of my old data become unreadable, and in the first place i did not see the deference between RAID 5 & 6 and you make it very clear thank you very much RAID 6 is the best in my opinion until now, and i will keep looking.
after all that can the user use same two drive specification with two different brands or there will be a problem with read write performance
Very good lecture and explanation is very nice .
With Software Defined Storage, the concept of hardware RAID is emulated at the driver and CPU level. ZFS, Ceph and Gluster are product families utilizing scalable storage. They generally have less performance (unless using SSDs for Cache and or RAM or nVME), but they scale very well and offer much more robust file integrity options.
Thank you very much. This is an excellent video. I am currently trying to recover important data from a failed RAID 5. After loosing a drive the entire RAID system failed. I still got 3 X 2TB drive saying good. What software can I use to access my data and copy them before I re create a new RAID. I need a prompt response because I need make decisions immediately as I am working on this currently. Thanks once more for the fantastic video.
Hello dear
at 34.52, I think Dear Mr. Asher you had mad a mistake, which is when you wrote 100 GB Disk capacity will lost. the correct is 50GB, because when you give the example of 4 disks each has 2TB, the answer was from your student was 2TB same as your example was.
I hope you get me dear.
Thank you too much for you.
At 28.33 what is the back up of the cancelled parity disk?
J Martinez, wow, thank you so much!!! I'm here wrapping my head around NetApp's RAID-DP, and you made it very clear!!! I think the only difference between RAID-6 and NetApp's RAID-DP, is that they use not one, but two dedicated parity disks. There's no striping of parity. I suppose that makes for even better performance? But, I wonder if rebuild is even slower? Thank you again!!!
Hi Martinez, Best and simple explanation.Thanks for producing such a tutorial. I have a small concern as below
When you are explaining RAID 5 - Parity at 28:25 th minute, you are stating as "It compresses the data and stripes across all the hard drives" I don't agree - it should be "it compresses the data and the parity is distributed across the hard drives. if the party also stripped we will have the disadvantage same as raid0 which simply there is no - fault tolerance for the parity. ( Simply Stripped data blocks with Distributed Parity)
Great lecture. Much appreciated
Very good lecture and explanation
Awesome explanation of Raid.
Thanks for posting & Sharing this
Mr. Martinez, Thank you. Very good, easyly understandable explanations of RAID topic. Great job.
Very good explanation.
excellent sir,you are a super teacher
Very well made and very explanatory
Wow! you are a wonderful teacher! perfect explanation with lots of visuals!
Clear, informative and well taught video. Thanks for the refresh and I subscribed your channel.
Great video. Excellent explanation! Congratulations to the lecturer
Realy clear teaching👍
RAID1: Depending on your RAID controller, RAID1 may have Striping on Reads, but never on Writes. There will be a performance increase on reads (the longer the read, the better the performance may get). Writes are nearly the same as a single drive, but since the drive has to do a "copy on write" the RAID1 array has to confirm two writes (at roughly the same time)... Latency (not speed) on Writes in RAID1 goes up slightly.
so clear and useful explanation
many thanks
Best explanation. Thanks.
hello Mr J.Martinez, I have been watching your video and it is very informative and I learn a lot from your lectures I just wanna ask about the raid 5 configuration. let us say you have 3 physical hard drives and each has a capacity of 2TB so your actual total would be 6TB, may question is if you set up in raid5 do you loose 2TB which is 1pc actual Harddrive or you will loose only 1TB? what will be the data storage amount will you loose?
superb and wonderfully explained,i like u very much the class.Thanks for asher college.......
Excellent! not many videos like this out there, this is how really things are explained. Thank you so much guys!! liking it and sharing it as well. ^.^
The RAID 5 Parity bit isn't "compressed" the way you describe. The RAID controller knows how many drives are in the RAID, then it counts the 1s for each block level. If there's an odd number of 1's the parity bit for that block level gets set to 1, if there's an even number of 1's the parity bit gets set to 0. If any single drive fails, you can reconstruct what the missing bit was by counting the number of 1's at each block level from the remaining drives and then figuring out whether it was a 1 or a 0 based on what the parity bit says it should be. There are more nuances to this explanation, but it doesn't use dictionary compression the way you explain... that would be far too slow and take up too much memory at this low-level of operation.
Yes, he's a bit flawed. This is what I think about his genius HDD buying guide: "Just because one hard drive sat on a shelf a bit longer than the other and at an other location( but from the same factory with the same specs), doesn't mean, that I's gonna fail sooner. To me, the lifetime of both starts, when they actually start using them (read and write), not at the time of manufacture. In case of new drives of course. Going with different brands (and manufacturing procedures), but the same specs would make more sense to me."
asher, you are awesome buddy. All my RAID concepts clear. Much appreciated. Thanks a lot!
nice video I've learned a lot thank you Mr. Asher
Very good way teaching . Thank you
Excellent explanations
Thank you! I've learned so much from this video. I have a question: my teacher (OS) said that RAID 1 has the highest rate transfer. It is true at all?
For Me, This is very good
Pleasantly and clearly explained! Many thanks!
9:10 You said having 10 hard disk drives is 90% of chance of losing all the data. However, if the pieces of information (chunks) will be divided by ten on each drive, doesn't that mean that the more drives you have the less read-write process each drive will have? If so, then can we say that the less drives we have, the more chances of fault we're gonna end up having because all the read-write processes will be focused on fewer drives? Just a thought I have.
Wouldn't a larger pool equal less work or read/write reducing failure chance? Or increased hdd life expectancy due to less read/writes?
Very well done explanation. thank you very much.
The chart in raid 6 is wrong. There ain't no drive dedicated to parity. As it says in the text.. Double DISTRIBUTED parity.
Awesome explanation! I have a situation where I have six drives in a raid 5 and lost two drives. Can you recommend any data-recovery software that might help me salvage my data?
You're screwed!
Excellent and exemplary video
I want to thank you very much for this video! I don't think I could have asked for a better explanation considering I got to practically sit in a classroom.
I do have one question - I do not understand how with RAID 5 or 6 the amount of backup storage requirements does not go up with an increase in data.
How can one hard drive size (with RAID 5) out of 8 hard drives backup everything in a hard drive failure? If each hard drive was 1 TB, why would there only be 1 TB needed for space whether it is out of 4 or 8 hard drives of the same size?
Masterr59 Parity is not exactly compression and it can't rebuild the other data alone. It uses the data of the other drives to calculate the missing info. Here's an example: Let's say a parity of 1 is stored for an odd sum and a parity of 0 for even. Striped on seven drives is 1 0 1 1 0 1 1. Since the sum is odd, 1 is stored in parity. So with one drive not working: 1 0 1 * 0 1 1, the parity of 1 says the sum is odd so the missing value must be a 1. Does not exactly work this way, but explains how parity works. It does not increase the more drives you add, but relies on the data on the other drives. Also explains why more than one drive failure makes a single parity of RAID 5 ineffective.
Excelent Professor !!!
How fast is RAID 5 compared to RAID 1? The video says it's faster, but my cousin said he did raid 5 and it was really slow (so slow that he had to switch to RAID 1).. Do you need a RAID card for the speed? Could it have been bad software or setup?
Good lecture on RAID