Hello,

 

I would to know which is the best mode configuring my drives to get the best performance.

 

My drives are: 2 SSD with  250 GB and 1 HDD 5200 RPM 4TB with 256MB cache.

 

In a normal Linux system I would make a RAID-0 with ZFS of my SSDs to get 500GB and my second drive as a normal HDD.

 

Which are the configuration options to make that in unRaid? Do you recommend me use the parity? Really I want to get the best performance, I think the possibles fails is not more important than performance in my case.

 

Actually I have each drive in the array but then, the performance is not like a RAID-0 because each VM use differents disks to save data.

 

Thank you very much for the help.

Regards.

 

 

 

See here for some information:

 

      https://wiki.lime-technology.com/UnRAID_6_2/Storage_Management#Cache_pool_operations

 

There is not a much of advantage to using unRAID on long term basis if you are not going to use parity for your array.  When you use a ssd cache drive setup running RAID1, your write performance will be limited to (1) the speed of your network (1Gb or 10Gb) or (2) the write speed of the drive.  Ditto for read speed both from the cache setup or the array.

 

The piece of information that is missing is what is type of usage pattern that you are doing where speed is paramount consideration---  Interactive Database operation or video editing are two examples that I could think of where speed could be THE major consideration.  Giving a few details might allow some users who are doing something similar give you their views. 

Edited November 20, 20178 yr by Frank1940

I will use it for:

 

1) Developer work stuffs, working with IDE, databases, Big Data, and similar.

1) Home purpose like playing games, write documents, see videos, etc.

 

Really I don't need the parity because my important documents are uploaded to cloud-services. Work or personal important information are in the cloud.

I am not an expert on hardware but I need the best speed to work without to be waiting for operations, or something like that. I have a I7 7700K, 16GB RAM DDR4 3000 and two GPU GTX970. So I don't want to lose performance by reading from a HDD at 5200 RPM.

Maybe a disk fails each 10 years? 5? I don't know but I think it is not important for me.

Then, is it possible to configure the unRaid for my purpose? Do I need to put disks in the array always? I thought cache-pool is for writing but not reading.

What do you think? Should I use the parity? or which is the mode I should configure my unRaid to get 1 disk RAID0 (2 SSD with 250GB each one) and another with 4TB (for saving data). Now putting all in the array mode it gets me 3 disks and non-perfomance of RAID0.

 

Or maybe a good option would be put another HDD as parity and my 2 SSD in RAID0 as disks to get the best reading performance. I don't know.

 

Thank you very much for the help!

Kind regards.

Edited November 20, 20178 yr by SnakeDrak

36 minutes ago, SnakeDrak said:

or which is the mode I should configure my unRaid to get 1 disk RAID0 (2 SSD with 250GB each one) and another with 4TB (for saving data). Now putting all in the array mode it gets me 3 disks and non-perfomance of RAID0.

 

You can assign the HDD to the array as a data disk and make a raid0 cache pool with both SSDs.

14 hours ago, johnnie.black said:

 

You can assign the HDD to the array as a data disk and make a raid0 cache pool with both SSDs.

 

Thank you johnnie . Then using the cache pool in raid0 mode could I save my VM data inside them? I understood the cache is for improve the write speed and in the night the data is passed to a normal HDD so when I go the next day to load my VM, it will be load very slow because it will be reading from a HDD and not from SSD.

I apologize for my knowledge about this topic, I try to understand it.

 

34 minutes ago, SnakeDrak said:

Then using the cache pool in raid0 mode could I save my VM data inside them?

Yes

 

35 minutes ago, SnakeDrak said:

I understood the cache is for improve the write speed and in the night the data is passed to a normal HDD so when I go the next day to load my VM, it will be load very slow because it will be reading from a HDD and not from SSD.

Each share can be set in various ways depending on your use case, you'd set the VM share to cache only and it wouldn't be moved to the array.

43 minutes ago, johnnie.black said:

Yes

 

Each share can be set in various ways depending on your use case, you'd set the VM share to cache only and it wouldn't be moved to the array.

 

Thank you again johnnie. But if I don't have a HDD for example and I want to put both SSD in the cache pool, would it be possible? I think when you try to start the array without disks in the array, it fails. Also if I put them in the array (I know is not supported oficially the SSDs in the array) the VMs save the data in DISK1 or DISK2 but it is not RAID0 so when the VM load the max size of the disk it will be busy and it will not use the second disk. Is it true?

Edited November 21, 20178 yr by SnakeDrak

1 minute ago, SnakeDrak said:

Thank you again johnnie. But if I don't have a HDD for example and I want to put both SSD in the cache pool, would it be possible?

No, you need to have at least one data disk assigned for the array to start.

2 minutes ago, SnakeDrak said:

Also if I put them in the array (I know is not supported oficially the SSDs in the array) the VMs save the data in DISK1 or DISK2 but it is not RAID0 so when the VM load the max size of the disk it will be busy and it will not use the second disk. Is it true?

Yes, raid0 is only possible in the cache pool.

Then if do I just have disks in the array (for example HDDs), will a VM use the size only in one disk?  I don't understand how the parity save the data because if I have two disks with differents sizes and differents data with a total of 8TB but the parity have 4TB... how is my data secured??

Again thank you very much. I understand it now better.

Edited November 21, 20178 yr by SnakeDrak

8 minutes ago, SnakeDrak said:

Then if do I just have disks in the array (for example HDDs), will a VM use the size only in one disk?

Yes, no file can span more than a single disk.

 

8 minutes ago, SnakeDrak said:

I don't understand how the parity save the data because if I have two disks with differents sizes and differents data with a total of 8TB but the parity have 4TB... how is my data secured??

https://wiki.lime-technology.com/Parity#How_parity_works

17 hours ago, SnakeDrak said:

I will use it for:

 

1) Home purpose like playing games, write documents, see videos, etc.

 

 

In my experience  Data is absollutly fine off UNRAID box.  For Games and editing videos / photos eg lightroom you are much better off having a large local SSD (it is what I do) then backing up from said local SSD to unraid.

8 minutes ago, schford said:

 

In my experience  Data is absollutly fine off UNRAID box.  For Games and editing videos / photos eg lightroom you are much better off having a large local SSD (it is what I do) then backing up from said local SSD to unraid.

If you are using a Windows (or other OS) VM to access your data on the unRaid server, all the disks on the server are "local". There is no network lag. IMO, this is a big reason that a Windows VM is better than a dedicated Windows workstation.

1 minute ago, SSD said:

If you are using a Windows (or other OS) VM to access your data on the unRaid server, all the disks on the server are "local". There is no network lag. IMO, this is a big reason that a Windows VM is better than a dedicated Windows workstation.

Thats an interesting point - I had never considered that.

 

Though thinking it through my main GPU which is a GTX 1080 lives in my main pc and that provides the acceleraiton for rendering in premiere pro and wouldnt want to pony up for one on my unraid box.

25 minutes ago, schford said:

Thats an interesting point - I had never considered that.

 

Though thinking it through my main GPU which is a GTX 1080 lives in my main pc and that provides the acceleraiton for rendering in premiere pro and wouldnt want to pony up for one on my unraid box.

 

If your Windows workstation is a VM, you don't need your dedicated Windows box any more. And your GPU can live inside the server.