Hardware RAID for cache


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Hi guys,

 

I have an LSI 9271-8i card lying around and not enough SATA ports on the motherboard for both array drives and cache SSDs on the system I am building now for unRAID.

I know passthrough is best, and JBOD would work too, and then I should leave redundancy to btrfs in raid 10 config for my SSD cache.

This card, unfortunately, does not have it mode firmware and I do not want to brick it by trying to flash one for 2308 chipset (although that might work according to Google).

What is the downside to use a good hardware RAID card for cache drive? I guess obvious one would be absence of smart info. Is there any way around that by monitoring the card and drive status by some other tool? Another one might be TRIM.

I am planning to use 4x 1.8tb SSDs for cache drive in raid 10 setup (got them for free, same as the raid card). I am planning to have most of my folders on the cache drive and let mover move it to the array overnight. So, I cannot risk loosing any data, and raid 10 makes sense.

If using hardware raid for cache is not the most terrible idea, what would be the best way - setup two RAID 0 virtual drives and let btrfs run software raid 1 on them or present raid 10 to unRAID as virtual drive? Or create 2 raid 1 virtual drives and then btrfs raid 0 in unRAID?

Or should I just get a 9201-8i from eBay and do it the recommended way? 

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Sounds like you have a pretty good handle on the issue, so my recommendation is follow your gut.

 

Others may have opinions for you, but only you can make the final decision over how much the hassle of manually monitoring the health of free stuff vs. spending money to go the easy route is worth.

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Is there a way to monitor the health of LSI hardware RAID from within unRAID? 

I seem to only find questions from other people asking if there is any way to run MegaCLI commands on unRaid, but all the responses are that they should use IT mode cards.

There is also a suggestion to use CA User Scripts but how could one run a script with a command that does not work within os?

 

EDIT later:

Ah, it is just a binary file which can probably be run from under unRAID. I'll give it a go and see it I can export monitoring info. 

Edited by ProxyARP
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Ok, did some testing, the drive info is visible via smartctl tool on the dev/bus/x

Command smartctl -- scan helped to find the name of the devices. 

A simple bash script running this command and parsing the output in a cron job should be able to monitor the status of the drives.

I was not able to run the binary of MegaCLI, was coming back with error that the binary cannot be executed or something like that. 
 

long story short, I was able to get a the H200 already flushed HBA for $40 and will be using this for simplicity 

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