Changing RAID Type Speed

[marcusd]

Hi There!

Just wondering why the speed to change RAID Types is so slow... I'm currently changing from SHR to SHR-2 on my RS2421+ and I have about 29GB of data. My CPU is usually around 1% utilization as per Performance Monitor and my DSM Desktop Read / Write is between 20MB - 30MB in Task Manager.

I turned off all Tasks like SMART Tests and Scrubbing (Automatically Paused) and have no other applications running... It's used as a file server for Plex with no additional software installed on it other than a basic DSM 7 install. My plex server is on a dedicated Windows computer with a Nvidia GPU. I even shut down Plex on my Dedicated computer so the NAS isn’t serving up any files while it is changing raid types, not that I needed to do that.

I've changed the RAID Resync Speed setting to "Run RAID Resync Faster" hoping that would speed things up. I added 2 new drives and selected both when going through the steps to change raid type as DSM said that it would be faster if it had 2 blank drives to work with even though I only needed 1 blank drive to change the raid type.

I just can't believe that it is moving this slow on a fairly capable machine with drives that can handle sustained read / write speeds of 150MB plus. It's as if DSM software itself is the bottleneck and not the hardware.

I'm currently on Step 1 of 4 and understand that it is the slowest of all the steps. It's seems the rest of them move pretty quickly. Does anyone know what the rest of the steps are? I assume Step 1 is the moving of data around on the drives.

It would sure be nice if they would do something with DSM to speed up the process. Not that it would solve my issue but for future users!

 

[Rusty]

You are expanading the array configuration by type and size. It will take time. It will make 2 passes in total (so 4 tasks). In certain models and raid types like RAID6, DSM7 will do this much faster as it will effect only the used space. In your case it will do for the whole array regardless if its full or empty. So with large drives, and in return a large volume, it takes time. It can take days for it to complete, and turning off services might help but if your CPU is not tasked that much there is nothing to do but wait.

 

[marcusd]

Thanks Rusty…. So I figure it’s going to take at least 2 weeks to complete Step 1 which I assume is part of the first pass.

Are you saying that it’s going to take another 2 weeks to do I guess step 3 as part of the second pass or does the second pass run faster?

 

[Rusty]

Thanks Rusty…. So I figure it’s going to take at least 2 weeks to complete Step 1 which I assume is part of the first pass.

Are you saying that it’s going to take another 2 weeks to do I guess step 3 as part of the second pass or does the second pass run faster?

The speed will not take weeks. The progress in % is not linear. You will see after about 24-36h how the progress will go.

 

[marcusd]

Ya I started it this past Sunday at 5:30PM so I’ve been about 109 - 110 hours now and I’m at 30% - 31% so extrapolating that I figure I’m a good 2 weeks.

I more or less am not familiar with all the steps in the process and was wondering if some of them run faster than others.

 

[Rusty]

Ya I started it this past Sunday at 5:30PM so I’ve been about 109 - 110 hours now and I’m at 30% - 31% so extrapolating that I figure I’m a good 2 weeks.

I more or less am not familiar with all the steps in the process and was wondering if some of them run faster than others.

Well can you share the size of the initial volume and drive composition as well as the new SHR2 setup and new drives? Are we talking about 18TB drives or what?

 

[marcusd]

Hey Rusty…

Initial volume size is 36.3TB with 29.3TB Used in an SHR RAID Format.

Yes I added 2 x 18TB drives to bays 11 & 12 to use to change my RAID Type to SHR-2.

Prior to the RAID change I had the following in SHR Format…
Bay 1 - 6TB
Bay 2 - 4TB
Bay 3 - 4TB
Bay 4 - 4TB
Bay 5 - 4TB
Bay 6 - 4TB
Bay 7 - 4TB
Bay 8 - 4TB
Bay 9 - 6TB
Bay 10 - 18TB

Thanks!

 

[Rusty]

Well that explains it. Not a small volume and it will be even bigger. You will just have to be patient.

 

[marcusd]

Ya figured as much…. Just would love to see things move faster during this critical time period. Especially since it appears that my hardware is barely breaking a sweat during this process.

 

[Coop777]

It is "breaking a sweat" - expanding from SHR-1 to SHR-2 adds additional stress to the entire disk array. This is due to the doubled parity calculations that (in the end) allow for 2 drives of redundancy. I am curious, why did you feel the need to change from SHR-1 to SHR-2?

 

[marcusd]

Hey Coop777

I felt that I’d rather have a 2 disk fault tolerance seeing as I have 12 individual Disks in my RAID. Plus the potential for up to 12 Disks more with an expansion unit, so 24 Disks in total.

Felt I should make the change now as it will only take longer with a lager volume size, additional disks, and larger disk sizes.

Had the spare drive bay(s) so figured nows the time.

 

[Coop777]

I ran it with my first NAS, but found that it takes a significantly longer amount of time to add expansion drives and there's a bit of a performance hit. For me, SHR-1 with an external backup is quite sufficient, I would not run SHR-2 unless it was for a business and managing critical data and uptime concerns.

 

[marcusd]

Ya I hear ya…. Unfortunately I don’t run a external back-up due to volume size. I know SHR-2 is not a back-up, but the added peace of mind of being able to handle 2 failed drives Allows me to sleep a little better at night. Nothing on it is mission critical and couldn’t be replaced, albeit it would take to time to replace it all!!

Performance wise this is a Video file server so I’m not really even coming close to the performance it is capable of when at most it’s serving up a few files at one time.

 

[Telos]

Unfortunately I don’t run a external back-up due to volume size

This is high risk. Grab a couple of 18 TB drives, and get cracking on that backup.