February 28, 201610 yr Hi, I have some questions about unRAID: 1. How unRAID works? im planning to use 6 2TB drives, and I dont know exactly what is the possible space available and disk fault tolerance 2. What happen if the parity disk fails? 3. unRAID supports LSI 9271-8i controller? for example: if I created a RAID 10 on controller, in unRAID I will see one drive? 4. If the answer for previous question is yes: it's recommended to create RAID with the controller or only with unRAID? I know it's ironic to use unRAID and not with his principal feature, but my first interest is to use for GPU Passthrough with a VM and NAS capabilities 5. SSD Cache only impacts on write speed? or also in read speed? PD: Sorry for my english and if this isn't the forum category for that questions
February 29, 201610 yr Hi, I have some questions about unRAID: 1. How unRAID works? im planning to use 6 2TB drives, and I dont know exactly what is the possible space available and disk fault tolerance 2. What happen if the parity disk fails? 3. unRAID supports LSI 9271-8i controller? for example: if I created a RAID 10 on controller, in unRAID I will see one drive? 4. If the answer for previous question is yes: it's recommended to create RAID with the controller or only with unRAID? I know it's ironic to use unRAID and not with his principal feature, but my first interest is to use for GPU Passthrough with a VM and NAS capabilities 5. SSD Cache only impacts on write speed? or also in read speed? PD: Sorry for my english and if this isn't the forum category for that questions 1. If you use 6 2 TB drives and assign one as your Parity Drive you'll have 10TB of storage. Your array will have single disk failure protection. 2. If the parity disk fails you've lost no data. Replace the parity drive, rebuild parity and you'll be parity protected again. 5. The cache disk only speeds up writes by delaying the process of writing to the parity protected array. It does not impact reads from the array at all. It does impact reads from cache-only shares (usually set up to be operational space for programs created with Dockers or Plugins)
March 4, 201610 yr Author Ah ok, thanks! Im really interested in use LSI controller with RAID 6 because is more secure (2-drive fault tolerance) and RAID 0 with 2 SSD for VM's but I dont know if UNRAID support this. Ahh, and the latest question: if I set a SSD for cache, I can use this for storage? or it's only for cache?
March 4, 201610 yr Ah ok, thanks! Im really interested in use LSI controller with RAID 6 because is more secure (2-drive fault tolerance) and RAID 0 with 2 SSD for VM's but I dont know if UNRAID support this. Ahh, and the latest question: if I set a SSD for cache, I can use this for storage? or it's only for cache? #1 Reason I prefer unRAID over a hardware based raid solution like RAID6 on a LSI controller: If you have one more drive fail than the fault tolerance you loose everything. So for RAID6 if you have 3 drives go bad at once - say you have one go bad and then while rebuilding you have two more fail for instance - you loose the whole array. If I have three drives fail with unRAID I only loose the data on those three drives and only two drives if one of the three drives that failed is the parity drive. I will never go back to traditional raid setup for long term storage of my files. I might use traditional raid for short term storage like in between times I move my recordings to my unRAID array.
March 4, 201610 yr I'm going to jump in with Bob on this, the main draw for unRAID for me was that if my fault tolerance was exceeded I'd lose less than everything. Part of the reason I started shopping around for software file server instead of hardware was because of a RAID5 failure while rebuilding the array... so I lost a lot of files, but thankfully I had some recovery by forcing the RAID to be valid and checking the CRC32 values. I then started dumping everything to unRAID using a spare box that ran a beta version of 6 as the docker functionality was very desirable to me.
March 4, 201610 yr Also unRAID allows you to mix disk sizes which is not something you can do with traditional RAID.
March 4, 201610 yr I'm going to jump in with Bob on this, the main draw for unRAID for me was that if my fault tolerance was exceeded I'd lose less than everything. Part of the reason I started shopping around for software file server instead of hardware was because of a RAID5 failure while rebuilding the array... so I lost a lot of files, but thankfully I had some recovery by forcing the RAID to be valid and checking the CRC32 values. I then started dumping everything to unRAID using a spare box that ran a beta version of 6 as the docker functionality was very desirable to me. Similar for me. I had an array of 12 200GB drives on a 3Ware hardware controller throw several drives at the same time and lost all of my data - all 2 TBs of it. Since I've been on unRAID I've only lost 200GB and that was because I made a stupid mistake when I put a 2TB cache drive full of data in to replace a failed drive and started to rebuild the drive. I caught it after 2-5 minutes and was able to recover all but 200GB of data with the file system tools for ReiserFS. I hope I would be as successful with the XFS disks I have now. But I also hope I never do something stupid like puting a full cache drive in to replace a failed drive again too!
March 5, 201610 yr I also hope you have your data in more than one place now, remember the 3-2-1 rule for backups. Three copies of your data, in at lest two different formats with one copy offsite. Not always possible to follow when at home, but its a good rule to try and follow.
March 5, 201610 yr Ah ok, thanks! Im really interested in use LSI controller with RAID 6 because is more secure (2-drive fault tolerance) and RAID 0 with 2 SSD for VM's but I dont know if UNRAID support this. Ahh, and the latest question: if I set a SSD for cache, I can use this for storage? or it's only for cache? Unraid is a software implementation of RAID so until V6.2 is released you can't get 2 drive fault tolerance. You can't use a hardware RAID setup in Unraid. I may be misinterpreting your above statement and if so, apologies, but thought I'd make it clear.
March 5, 201610 yr People do use hardware RAID controllers for redundant cache drives. I think it is most commonly done with Areca controllers? This isn't done very often, though. And under unRAID 6 BTRFS cache pools are the standard way to get redundancy in the cache subsystem.
March 5, 201610 yr People do use hardware RAID controllers for redundant cache drives. I think it is most commonly done with Areca controllers? This isn't done very often, though. And under unRAID 6 BTRFS cache pools are the standard way to get redundancy in the cache subsystem. Didn't realise he was talking about the cache drives, my bad......
March 6, 201610 yr Author Ah ok, thanks! Im really interested in use LSI controller with RAID 6 because is more secure (2-drive fault tolerance) and RAID 0 with 2 SSD for VM's but I dont know if UNRAID support this. Ahh, and the latest question: if I set a SSD for cache, I can use this for storage? or it's only for cache? #1 Reason I prefer unRAID over a hardware based raid solution like RAID6 on a LSI controller: If you have one more drive fail than the fault tolerance you loose everything. So for RAID6 if you have 3 drives go bad at once - say you have one go bad and then while rebuilding you have two more fail for instance - you loose the whole array. If I have three drives fail with unRAID I only loose the data on those three drives and only two drives if one of the three drives that failed is the parity drive. I will never go back to traditional raid setup for long term storage of my files. I might use traditional raid for short term storage like in between times I move my recordings to my unRAID array. That's is the reaspon why im asking about how works unRAID (or intepreting based on my questions). I thought the unRAID 6 is similar to RAID 5 (clearly I was wrong so thanks!). I have doubts still about hardware RAID 0 on unRAID 6. I want to place VM on dual SSD RAID 0 for get performance. SSD RAID 0 is not for cache (but in a possible case it would be useful to know) because it does not impact read speed. I read that it was possible to use drives that were not part of the unRAID array for VM like SSD or another drive, so I want to do a RAID 0 with LSI controller for this purpose. I can't use another controller because I have an LSI controller. PD: Again, sorry for my english
March 6, 201610 yr Ah ok, thanks! Im really interested in use LSI controller with RAID 6 because is more secure (2-drive fault tolerance) and RAID 0 with 2 SSD for VM's but I dont know if UNRAID support this. Ahh, and the latest question: if I set a SSD for cache, I can use this for storage? or it's only for cache? #1 Reason I prefer unRAID over a hardware based raid solution like RAID6 on a LSI controller: If you have one more drive fail than the fault tolerance you loose everything. So for RAID6 if you have 3 drives go bad at once - say you have one go bad and then while rebuilding you have two more fail for instance - you loose the whole array. If I have three drives fail with unRAID I only loose the data on those three drives and only two drives if one of the three drives that failed is the parity drive. I will never go back to traditional raid setup for long term storage of my files. I might use traditional raid for short term storage like in between times I move my recordings to my unRAID array. That's is the reaspon why im asking about how works unRAID (or intepreting based on my questions). I thought the unRAID 6 is similar to RAID 5 (clearly I was wrong so thanks!). I have doubts still about hardware RAID 0 on unRAID 6. I want to place VM on dual SSD RAID 0 for get performance. SSD RAID 0 is not for cache (but in a possible case it would be useful to know) because it does not impact read speed. I read that it was possible to use drives that were not part of the unRAID array for VM like SSD or another drive, so I want to do a RAID 0 with LSI controller for this purpose. I can't use another controller because I have an LSI controller. PD: Again, sorry for my english I know people are using Areca cards to create Hardware raids for Catch and/or Parity drives so you should be able to create a Raid0 catch drive if you want. I've never done that myself. My VMs are on my WD VelociRaptor. Not as fast as an SSD - but I had them (WD VelociRaptor). So I wanted to use them for something and they work acceptably for me. But my VMs like the unRAID servers are headless. I'm not trying to setup a NAS Gaming machine.
March 6, 201610 yr If you have a disk controller card that can manage a disk array, and present the array to unRAID as if was a single disk then you can do whatever you want as unRAID is not aware there is an array underlying the single logical drive. However you are then dependent on the recovery facilities offered by the card if any problems occur.
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