Cache drive replacement? doing it easy or wrong?


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Hi Guys,

I am looking to "upgrade" my cache drive and want to know if my "easy" way of doing it will work or if it will cause trouble.

I was just going to shove my larger SSD into the system and tell it to use it as cache parity drive. Then once its all synced up then remove the old SSD cache drive.

 

I have searched how to upgrade the Cache drive and everyone seems to do it manually, so I wanted to ask if my lazy way would work or if I have to do it manually for a reason.

You may be wondering why I don't just leave the old one there for Parity. Well I am going down the route of changing motherboards to a dual socket server board which does not have any M.2 to be able to use the current Cache drive so I want to swap from it (256GB) to a SATA (1TB) SSD that I have lying around. Because I no longer do anything directly on the UnRaid server the loss of speed from the NVMe is no penalty as network infrastructure would be the bottleneck.

 

Thanks for any thoughts and or feedback

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11 minutes ago, trurl said:

Depends on the answer to some questions. The easy way to get the answers is to

 

Go to Tools - Diagnostics and attach the complete Diagnostics ZIP file to your NEXT post.

I'm happy to include a diagnostics file but I'm not trying to diagnose anything. How would that be useful?

I want to know if making the SATA SSD a Parity Cache drive. then removing the M.2 drive from the system is a safe way to go about swaping drives.

I cant think why it wouldn't work but, has it been done? I'm just asking before I try it, in case I have overlooked something major.

Thanks

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10 minutes ago, pyrosrockthisworld said:

I'm not trying to diagnose anything. How would that be useful?

29 minutes ago, trurl said:

The easy way to get the answers

to my questions without having to ask them, possibly requiring multiple posts that might even take a while since I might go to bed soon.

 

Cache pools technically don't have parity disks. What filesystem is your cache now?

 

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Why do you have 500G allocated to docker.img? 20G should be more than enough and if it grows beyond that you have something misconfigured.

 

Why are your dockers and VMs not configured to stay on cache (appdata, domains, system shares)? Docker/VM performance will be impacted by slower parity updates and will keep array disks spinning since they will have open files.

 

Not sure why you would care about your "easy" way of upgrading cache since it isn't clear you have anything important on cache anyway.

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The 500G docker.img was because I was troubleshooting something and I forgot to change it back, thanks for reminding me.

 

As to the docker and vm not on Cache, I am unsure, I don't remember changing anything but it could be because I only installed the Cache later down the track. Though I believe some of the Vdisk.img are on there. Any hints on remedying that would be appreciated.

The Cache also gets used for when dumping files onto the server as fast as possible, so that I can get them in a second location after I for example pull footage off a camera.

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The simple thing to do would be to just get everything moved from cache, replace cache, then get everything that belongs on cache (appdata, domains, system) moved back to cache. And along the way recreate docker.img at only 20G.

 

As for getting things moved, Mover will move cache-yes user shares from cache to array. And it will move cache-prefer user shares from array to cache. But, mover can't move open files, so to get things moved, you will have to disable Docker and VM services in Settings. Also, mover won't move duplicates, so it is possible there will need to be some manual cleanup along the way.

 

Now that I have explained the basic ideas and the reasons for them, I will give some steps to accomplish parts of this. We will take new diagnostics along the way to see the results and determine what needs to be done.

 

Starting in my next post in this thread.

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  1. Go to Settings - Docker and disable Docker. Also, delete docker.img from that same page. There are several other changes to make here later. Don't enable Docker again until instructed.
  2. Go to Settings - VM Manager and disable VMs. Don't enable VMs again until instructed.
  3. Go to each of your User Shares and set them to Use cache: Yes
  4. Go to Main - Array Operation and click Move. Wait for it to finish.

Then post new Diagnostics.

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You might want to consider using the latest beta since you are doing a new SSD. It has a new partition scheme for SSDs that make them more efficient, as well as multiple fast (cache) pools. I have a fast pool consisting of 1 NVMe for my dockers and VMs, and another with 2 mirrored SSDs for caching.

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31 minutes ago, trurl said:

You might want to consider using the latest beta since you are doing a new SSD. It has a new partition scheme for SSDs that make them more efficient, as well as multiple fast (cache) pools. I have a fast pool consisting of 1 NVMe for my dockers and VMs, and another with 2 mirrored SSDs for caching.

I've just rebuilt my server and installed a NVMe and a second SDD because I was looking to do that exact same thing you've got. I was going to setup the NVMe as unassigned and move the dockers and appdata there as googling showed there are a few people doing that to improve the performance.

 

With 6.9 and multiple pools, does that provide the same performance gains as an unassigned drive?  I was waiting for 6.9RC before dipping my toes in but I might move a bit faster if it will give me what I wanted without needing to make too many chages.

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Here is the 6.9beta25 thread:

 

https://forums.unraid.net/bug-reports/prereleases/unraid-os-version-690-beta25-available-r990/

 

I actually did the multiple pool setup on beta22:

 

https://forums.unraid.net/bug-reports/prereleases/unraid-os-version-690-beta22-available-r955/

 

But when the new partitioning for SSDs came out I redid them on beta25.

 

So, I have moved appdata, domains, system shares around quite a bit lately. The multiple pools especially came in handy for the repartitioning, since I just moved them manually with mc between the SSD pools so I could repartition. Much faster than getting Mover and the parity array involved.

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On 8/17/2020 at 6:27 AM, trurl said:
  1. Go to Settings - Docker and disable Docker. Also, delete docker.img from that same page. There are several other changes to make here later. Don't enable Docker again until instructed.
  2. Go to Settings - VM Manager and disable VMs. Don't enable VMs again until instructed.
  3. Go to each of your User Shares and set them to Use cache: Yes
  4. Go to Main - Array Operation and click Move. Wait for it to finish.

Then post new Diagnostics.

OK, here is the new diagnostics

Is now a good time to upgrade to the beta?

tower-diagnostics-20200818-0631.zip

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