Replacing Upgrading

[Govnah]

I have a QNAP TVS-882 with 2 SSDs in a RAID where most of my apps and system is installed. They are setup in a RAID 1 and I would like to replace/expand those drives. I assume I just need to dynamically pull one drive out and let the system rebuild the RAID followed by the 2nd drive?

Also, when I set this up initially I was new to QNAP and installed an M.2 drive and I use that has a caching drive, which I assume is fine.


Thanks

[Don]

Follow the directions in the manual for replacing the drives.

I hope you are not using a single drive for read/write cache.

[Govnah]

Yup I will take a look at the manual. Yes, I am using 1 M.2 drive for caching, from what I am hearing I may need to add an additional M.2 and setup as RAID0 and the enable that RAID0 as a caching drive?

Thanks

[Don]

If you are doing R/W caching you need to set up RAID 1. Anything else and you risk losing data if a drive fails.

[Govnah]

Wait, I have one physical drive M.2 that is use as a caching drive for the RAID5 volume, 20TB. Are you telling me if I lose that single M.2 caching drive my RAID5 volume would fail as well?
I have thought the caching drives, well just caching drives and if they failed I could just replace as needed and the only down-side is I would not have caching enabled for which every volume there were attached to and in this case my RAID5 20TB volume.

I was going to be adding an additional M.2 and attach it to my other volume, RAID1 (system and apps) that consist of SSDs.
Now what I think I am hearing I need to add an additional M.2 create a RAID1 and assign it to one volume. What I was going to do was add the additional M.2 and use that as an additional caching drive for my other volume RAID1 (system and apps).

Question, given the M.2 drives have a high-bandwidth my thought they would provide the greatest benefit as caching drives, or should I move the system and apps to the M.2 and use the SSDs as the caching option.

Yes I am reading best practices currently..."Use mSATA and SSD drives for Read/Write caching available on QTS 4.2.0, using 2 or 4 SSD and create RAID 1 or 10 as the caching pool. See Fig. 1 & Fig. 2"
Looks like I answered my question, I needed to create a RAID1, if I lose that caching drive I'm toast.
If I remove caching from one of my volumes/RAID5 to reconfigure and add back will I lose my data on the RAID5 volume? Plan is to add an additional M.2 (2-Samsungs 500GB) configure as RAD1 and add back. From what I am reading I should be able to provide caching for both volumes (RAD1/System/Apps and RAID5/data)?

Is 500GB overkill for a caching volume I currently have a 250GB crucial and would either add an additional 250GB crucial (cheapest) or upgrade to 2-Samsunng 500GB Pro, if that wouldn't be a waste of money.


Thanks

[storageman]

Wait, I have one physical drive M.2 that is use as a caching drive for the RAID5 volume, 20TB. Are you telling me if I lose that single M.2 caching drive my RAID5 volume would fail as well?
I have thought the caching drives, well just caching drives and if they failed I could just replace as needed and the only down-side is I would not have caching enabled for which every volume there were attached to and in this case my RAID5 20TB volume.

I was going to be adding an additional M.2 and attach it to my other volume, RAID1 (system and apps) that consist of SSDs.
Now what I think I am hearing I need to add an additional M.2 create a RAID1 and assign it to one volume. What I was going to do was add the additional M.2 and use that as an additional caching drive for my other volume RAID1 (system and apps).

Question, given the M.2 drives have a high-bandwidth my thought they would provide the greatest benefit as caching drives, or should I move the system and apps to the M.2 and use the SSDs as the caching option.

Yes I am reading best practices currently..."Use mSATA and SSD drives for Read/Write caching available on QTS 4.2.0, using 2 or 4 SSD and create RAID 1 or 10 as the caching pool. See Fig. 1 & Fig. 2"
Looks like I answered my question, I needed to create a RAID1, if I lose that caching drive I'm toast.
If I remove caching from one of my volumes/RAID5 to reconfigure and add back will I lose my data on the RAID5 volume? Plan is to add an additional M.2 (2-Samsungs 500GB) configure as RAD1 and add back. From what I am reading I should be able to provide caching for both volumes (RAD1/System/Apps and RAID5/data)?

Is 500GB overkill for a caching volume I currently have a 250GB crucial and would either add an additional 250GB crucial (cheapest) or upgrade to 2-Samsunng 500GB Pro, if that wouldn't be a waste of money.


Thanks

You should not add or remove caching while there is a potential for data IO to the volume.
RAID 1 is always advised for cache drives because if you lose write cache you lose what's temporarily in the cache hence data can get corrupted. Loss of read cache matters less as its recoverable.
The bigger the cache the better for reads because more data can stay in cache and be read ahead, bigger cache drives have less impact on writes because writes don't stay long.
Loss of cache can be very damaging for image type files such as ISCSI file or block LUNs or VMs but generally speaking volumes can persist with loss of write cache - though clearly it's something to avoid corrupting files!

[Govnah]

Strongman thanks for the reply. I read and validated on the NAS I have the option of removing the cache drive and adding SSDs. My plan is to make sure I have a good replicated backup and then remove the current M.2/cache drive and adding back 2 M.2s configure as RAID1 and assign to my volumes accordingly. I assume after reading this is correct approach and prevent any corruption while the cache is being removed as instructed.

From an OS/System/Apps perspective (2 SSDS RAID1) I can actually go into storage - manage and use the utility accordingly to replace each drive.

Again, thanks for the replies and if I missed anything please let me know.

[storageman]

Sure, should be no problem adding back later. It's removing where's more risk.
If a cache drive fails you can replace and let re-sync just like a standard volume RAID group.

[Don]

@Govnah - you never specified if you were using read/write caching or read only caching. For R/W use RAID 1 or 10. For RO use whatever you want.

[Govnah]

I am using RW and will change to RAID1 once I add an additional drive.

Thanks

[Trexx]

Just turn Ssd caching off and remove the drive from caching in storage manager and you will be fine until you get your 2nd m.2. You could add it back as a read-only cache drive in the interim if you like with no risk.


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