2 cache drives or increase mover?


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Hi all.

 

Im concerned that when my 1tb NVME cache is sitting full of data, any failure would mean losing it.  I've changed the mover settings to 'Every 2 hours' because that way i would only ever lose 2 hours work.  

 

Am i understanding that correctly?  Is there any downside to doing this?  If i can avoid buying another 1tb NVME as parity then brilliant but if i have to i will.

 

What are your thoughts?

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I think you should reconsider how you are using cache. A 1TB cache should never get full. And making mover run more often will likely just get in the way. Mover is intended for idle time. It is impossible to move from faster cache to slower array as fast as you can write to faster cache, and moving while still writing is going to make things even worse.

 

I recommend not caching initial data load at all. After that, how much do you really expect to write to your server daily?

 

If you want more detailed recommendations post your diagnostics.

 

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1 minute ago, Genesius10 said:

well youve sort of answered my question.  im trying to move a lot of data and its filling the cache so i increased mover frequency.  i think my 1tb cache will be fine once i have everything up and runnning.

Mover will be clearing the cache MUCH slower than you can fill it.    That is the rationale behind recommending by-passing the cache during initial data load when  you will be moving more data in day than you can fit onto the cache.

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I guess it really depends on how your using your Cache drive.

Are you seriously moving so much data that you need to empty it so much or do you have so much simply siting on your Cache for instant access that you aren't moving it? You might just need to rethink how your using your Cache drive settings per share. 

 

Because you do have options. 

You can use your Share set to Cache only so no data leaves it.

You can use your Share set to Prefer so it keeps it on it and when its full starts dumping to Array until your cache is empty enough then returns back.

You can use your Share set to Yes so it moves on a set time aka every 2hours or whatever you choose.

You can use your Share set to NO so it moves data directly to the array and bypasses the array.

 

I use some of the above in certain situations

- My dockers are set to Cache only

- I don't really use Prefer

- Most of my Shares are set to YES so everything writes fast and is moved to my array 1x a week. FYI I do use a 1TB SSD.

- My wife's share is set to NO because she uses her share 1 or 2 times a month for backing up Family stuff, photos and whatever she considers                   important and it goes straight to protected array. Then when I remember I back it up to a USB portable drive offline.

 

 

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