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emrepolat7

Unraid with Hardware Raid 5

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Hi Guys;
I am playing with unraid for last two days. I really enjoyed it and have some questions. First let me tell you about my setup.
•    HPE ML110 Gen10 4208
•    HPE Smart Array P408i-p SR Gen10 
•    64 GB Ram
•    3 x 4TB SATA HD
With using HPE Smart Storage, I have created raid 5 logical storage drive. I installed unraid trial version. Unraid detected my hard drive as one 8TB logical drive. I have zero problems with installing vm (macos, windows, linux)  docker, apps vs so on. 

My questions are;
1) With this setup I do not have any Parity disk. Is this going to be a problem? Since I have a hardware raid 5, I believe all my data should be fine against any hard disk failure.
2) In the future, I believe I can add more disk to my Raid 5 Storage. Is it so?
3) is there any things that I should be careful about this setup?
Any recommendation are welcomes...

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Posted (edited)
On 6/9/2020 at 9:21 AM, emrepolat7 said:

Hi Guys;
I am playing with unraid for last two days. I really enjoyed it and have some questions. First let me tell you about my setup.
•    HPE ML110 Gen10 4208
•    HPE Smart Array P408i-p SR Gen10 
•    64 GB Ram
•    3 x 4TB SATA HD
With using HPE Smart Storage, I have created raid 5 logical storage drive. I installed unraid trial version. Unraid detected my hard drive as one 8TB logical drive. I have zero problems with installing vm (macos, windows, linux)  docker, apps vs so on. 

My questions are;
1) With this setup I do not have any Parity disk. Is this going to be a problem? Since I have a hardware raid 5, I believe all my data should be fine against any hard disk failure.
2) In the future, I believe I can add more disk to my Raid 5 Storage. Is it so?
3) is there any things that I should be careful about this setup?
Any recommendation are welcomes...

Here im specifically NOT speaking about licence-issues this may cause,  storage based linux distro's like unraid  normally entail that they are in charge of your storage completely. meaning that 'they alocate drives to an aray, manage the agray, and set and check parity.   so when you use a thing like hardware raid  the whole computere (even the uefi or bios) sees your aray as a single disks.   

 

Being the geek that i am i would say that this might actually be a slight loophole in how licencing is enforced:  by alowing you to have more hardrives connected  as you could end up having   x raid 5 volumes instead of just x drives 

BUT.
  1: its kind of cheating  and i would recomend to pay for pro regardless. 

  2: these hardware raid controllers cost you way more than a licence-upgrade anyway, 

  3: hardware raid has 1 huge drawback over  software defined solutions. 

      IF your raid card brakes, you need an exactly identical (sometimes up to the firware revision)  card to restore your storage pool.  Diferent brands  or even diferent models of same brand card often do not fully comply to the same storage-logs formats  where you may end with a broken storage pool still. 

 

That for background info: 

Now your question:  Yes you will get parity but not from unraid. raid3  and 5 have thair own inbuild parity systems  quite the same way as unraid does it  but with them its done on the controler-card by a special-purpose controller chip (hence hardware raid) 

 

In theory you could even add more disks to your system with other raid contollers and have unraid  calculate parity over the total bunch. this would effectivly  set you to  something quite near   raid 35*  However the question remains if you'd want non-readable-data-disks in case of failure of one of your raidcards or its raidpools.  or when cards get  EOL ... who/what monitors the raid5 levels and read errors of your drives  if not unraid as it has no way to detect your harddrives directly.  



* in therms of speed and efficiency the unraid system is mutch like  raid 3 (instead of 5) with only one less drawback (readeble data disks)

 

Edited by i-chat
spelling grammer and more.

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Thank you for your reply and comment.

 

However, I think you missed an important point in your comment about the license.

 

Why do we pay for the Unraid license; for kvm, for Docker or for custom software raid solution or for all the above?

Looking at the licensing model, (it depends on the number of disks); I conclude that we pay for the special software raid solution. Besides, most of the other features are already free products.

 

Even though you recommend me to buy a pro version, I think it should be the opposite; I should stuck with the basic version.

 

The reason I think this is that I am not going to use unraid software raid solution which is the main feature of unraid. As you mentioned, my raid solution is different and I have already paid for that within my hardware.

 

Although I will not use the original feature of the unraid, I am ready to pay because of many other amazing futures.

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My word of caution would be that you are planning on trekking into somewhat uncharted territory. Since you are planning on using a configuration that is not officially supported (to my knowledge) you will likely have trouble finding other forum users who have the requisite knowledge to provide support should you encounter problems. 

Also worth mentioning to new users looking to go off the reservation, despite being built on top of Linux unRAID is not just another distro. Its more like a purpose built NAS appliance OS. Just because something is easy to do, or well supported in most common distros, doesnt mean it will be possible in unRAID. I dont know if it will effect your particular situation, but it is often a stumbling block for people coming in without a clear understanding of what unRAID is (who also tend to be the crowd coming in wanting to something beyond the normal use case).  

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Thanks for your warning and concerns, I am testing the unraid for almost a month now.

I will try to answer you by sharing my experience about unraid. Although these are from my point of knowledge. As a user, I can say that I am neither a beginner nor a pro.

In my opinion, unraid consists of two main parts. A major part is the software raid and the other part is the well-polished and applied kvm, docker, system settings and plugins etc on top of Slackware.

 

First Part;

I already covered the first part of unraid hardware-wise. Besides, I have a Synology (how ironic, that is also a software raid solution) NAS appliance. Therefore, your concern about getting support for this part is irrelevant in my situation.

 

Second Part;

What a coincidence that, Slackware was the first Linux distro I have ever installed back in the 1990s (from floppy disk!) and I continued to install and experiment with it on and off (along with a half dozen other distros).

I would love to know the origin of this quote, but it is very old and it goes something like this:

"Learn Red Hat and you’ll know Red Hat; learn SUSE and you’ll know SUSE; but learn Slackware and you’ll know Linux."

 

What I am trying to explain is that, everything in the other part is all about well-known software and their configurations. Therefore, when I have a problem, this forum is not the only source that I will be searching for the solution.

 

Above all, unraid really impressed me with its simplicity and robustness. Everything is very clear. You do not lose control over the OS. Setting files and locations of all applications are certain and simple.

All my OS and OS config files in the "/boot" folder. All my data, apps, apps data, docers, vms and their configs are in the "/mnt/user(disk1)" folder which is my xfs formatted disk.

Even if something goes wrong, I can mount and access that files from any live OS.

It is almost perfect for me.

 

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Hi - Unless I missed it, there is little mention above of the significant disadvantages of the RAID 5 approach. 

 

Firstly, all of the drives need to be the same size.  You cannot mix and match as needed, which you can do with Unraid.  You can't upgrade your parity drive and a data drive to new larger drive sizes while still leaving your old data on much smaller drives.  With Unraid that's easy, meaning that you can expand storage as and when needed and using drives based on your needs rather than the needs of the existing array. 

 

Second, what happens if two drives fail?  With Unraid, you can take any data drive out of that machine and read it on another Linux system since each disk (except the parity disk) contains a stand-alone file system and no files are spread across more than a single drive.  If you lose two drives from a RAID 5 array you often effectly lose everything.  If you have a second parity drive in Unraid, you can have have two drives fail and still suffer no data loss; lose three and you only lose the data on those drives.

 

So rather than looking at the licensing etc, I would look at how you use the system, how future proof is it, and how robust is it in the event of a multiple drive failure (and they do happen sometimes).   THe only plus of RAID 5 is that it may be faster when writing, and even that can be mitigated by using a cache drive or the "reconstruct writes" setting for the array. 

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Guys, please, let's not be confused by some fundamental basics.

 

Your First comment dully noted.

 

However your second comment is misleading. Raid is not a backup. So what is it? 


Uninterrupted continuity in the event of hardware failure : the main reason to use RAID is to protect your data against drive failure in real time. It gives you immediate data protection and continuity, since internal drive failures can happen at any time.

That’s something backups can’t do. If you’ve just got one hard drive and it fails, it’s going to take time to replace that fried drive before you even transfer your backed up data onto it. That hardware replacement time means a disruption of business.

Even if the backup solution reduces the recovery time to a few minutes, what it can’t eliminate is the time it takes for you to find a new working drive and install it.

 

Please let's use what ever we use but knowing what it is. For example; I am using the most dangerous setup of Raid which is Raid 5 with 3 disks. 

 

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22 minutes ago, emrepolat7 said:

Uninterrupted continuity in the event of hardware failure : the main reason to use RAID is to protect your data against drive failure in real time. It gives you immediate data protection and continuity, since internal drive failures can happen at any time.

That’s something backups can’t do. If you’ve just got one hard drive and it fails, it’s going to take time to replace that fried drive before you even transfer your backed up data onto it. That hardware replacement time means a disruption of business.

Even if the backup solution reduces the recovery time to a few minutes, what it can’t eliminate is the time it takes for you to find a new working drive and install it.

You misunderstood backup and RAID concepts.

 

RAID is about the method that is used to store data. e.g.

  • RAID-0: stripe data across multiple drives
  • RAID-1: mirror data across multiple drives
  • RAID-5: stripe data + 1 parity block
  • RAID-6: stripe data + 2 parity blocks
  • Unraid: no striping, parity block is on a dedicated drive
  • etc.

 

A backup is a redundant independent copy of your data i.e. it's about the nature of the data.

  1. Redundant means you don't access (i.e. use) the backup data as part of your business-as-usual activities, outside of the window which you restore from / update the backup.
  2. Independent means the backup can be used on its own without needing all or part of the original data
  3. Copy means there are multiple instances of the data (i.e. the backup is NOT the original).

 

You can store a backup on a RAID array, just as you can store the original version of the data on a RAID-array.

RAID provides resilience to failure but on its own is not a backup because none of the RAID implementation, including non-standard RAID (e.g. Unraid) can satisfy all 3 criteria of being a backup.

  • RAID-0: fail all 3
  • RAID-1: fail (1)
  • RAID-5: fail (2), (3)
  • RAID-6: fail (2), (3)

 

So RAID is like having a spare wheel for your car; a backup is like having another car all together.

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Simply, we are saying the same, what I want to say is raid is not a backup. But I did not understand why you quote my very solid statement. Maybe, you did not read the comment of S80_UK that I answered.

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To sumarise:  i dont pay for pro: The reason I think this is that I am not going to use unraid software raid solution which is the main feature of unraid. As you mentioned, my raid solution is different and I have already paid for that within my hardware. 

 

you pay for the entire product, based on the intire system, its updates etc.  - its licence states: more than six  = higher licence, 

what you say is: i dont pay my (full) house rent because i dont often use the shower, as i like my GF's house's bathtubb. 

thats strange.  

 

for the rest whas my remark only in case of exeading 6 disk limit ofcourse 

 

im stil wondering on how you intend, to incorporate the  raid-level-status, diskstatus etc into the management UI 

or else how to get notified on disk-errors or raid errors etc. 

 

 

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Debate about licensing is meaningless since I am very sure that developer is well aware of this. Besides, I am sure I am not the only one in this situation.

 

11 hours ago, i-chat said:

im stil wondering on how you intend, to incorporate the  raid-level-status, diskstatus etc into the management UI 

or else how to get notified on disk-errors or raid errors etc. 

 

HPE iLO & HPE Agentless Management & SNMP

Edited by emrepolat7

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