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I have Adaptec 51245 controller (I know it is old but I got it for free) that I use in my server.

As far as I know it is highly recommended to use ECC RAM as system memory, but what about RAID controller? It has 512MB DDR2 RAM. Should I turn it off? I do not want any data corruption.

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ECC is essential for (large) server memory. Whether you need it somewhere else depends on your environment and your requirements.

Data sitting in memory for a long time is subject to corruption. DRAM bits can flip on their own with an extremely low probability - however, that probability can significantly grow in electrically noisy environments or with elevated levels of (background) radiation. So, if you either cannot tolerate any bit errors ever or the location is subject to EMI or radiation you practically cannot live without ECC.

That said, RAID controllers without cache perform very poorly. This is in part caused by the additional latency they introduce into the data path and may get really significant when used with a RAID variant that actually requires cache, like RAID-5 or RAID-6. You can use RAID-5 or RAID-6 without cache but the write amplification will kill you.

Does the computer have ECC support for its main memory? If not, the RAID won't make a difference. If you want to eliminate all data corruption risk (it's very low for moving data anyway) you can try without cache. Likely, you won't like the performance, so you should consider getting a RAID controller with ECC support and main memory with ECC.

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You can doesn’t mean you should. Don’t experiment here, you’ll save pennies literally on non-ECC memory, but you risk your data indeed.

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    basically doing just that, experimenting. I am a student running server for testing. I got that raid controller for free and now I am using it, for now cache is off, but I am not sure if I will put the data at risk if i turn it on? (if yes I won't buy new controller, I will just use this without cache) – jojo Jun 9 at 12:58
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    You'll benefit from learning something recent and decent like say MDRAID or maybe ZFS, hardware RAIDs are legacy (obsolete?) tech and you won't see them around soon. IMHO. – BaronSamedi1958 Jun 10 at 11:03

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