I saw a video that suggested 10% for your cache to storage when building your NAS....

[Quozl]

I'm baack, .

 

I've built a NAS out of my old computer with six 6TB drives, an old SSD SATA drive thats somewhere between 150-250 Gb. 

 

I'm using Unraid as suggested by a User and I've had some fun with it since then.

 

After doing some tests I see that I have some damage starting in that old SSD drive, and I've seen that the smart way to go forward is to use 2 drives for cache to protect against a dying drive during data saves.

 

So when I installed it made 1 of the 6TB drives a parity drive leaving 5*6TB for my data storage. Extremely rough math says thats 30TB and with the suggested 10% cache to storage ratio I'm looking at 3TB.

 

So (I was going to go with two 2TB Crucial ( https://www.amazon.ca/Crucial-MX500-NAND-SATA-Internal/dp/B003J5JB12/ref=sr_1_9?crid=3LK2PQZ2JWH0&keywords=2tb%2Bcrucial%2Bssd&qid=1702445143&sprefix=2tb%2Bcrucial%2Bssd%2Caps%2C251&sr=8-9&ufe=app_do%3Aamzn1.fos.d0e27fc4-6417-4b26-97cb-f959a9930752&th=1 )

drives.

 

My amazing wife asked me if the 4 TB drives were on sale and if it was worth it to go that route. I think it's serious overkill, but again, I'm turning to those with more knowledge.

 

This will be used to store our media (movies music and photos) and to be a Jellyfin media player to our 4K 85" tv. I say this only because I've read that pushing out the data for the bigger 4K TVs is harder than a small tv. Not that I think cache is involved with playing movies and music back, but I could be 100% wrong! 

 

The old computer uses a P67 Sabertooth M0b0 that has 8 sata ports thankfully.

[Quozl]

 

 

this is where I heard the 10% suggestion. And after rewatching it, I noticed that he mentioned if I'm going dual drives for parity then you'd need to double it. as each drive would be responsible for that 10% for parity. so maybe her suggestion for getting a pair of 4TB SSD drives isn't way overkill?!?!!

 

[Electronics Wizardy]

How much are you writing to your NAS? 

 

Unraid only has a write cache, it won't help with read speeds at all, and that video seems to go over other nas units that handle caching differently. That 10% rule doesn't apply to unraid, as it does caching differently.

 

If write speeds aren't a big issue or your on 1gbe you can consider having no cache.

 

 

[Quozl]

thank you so much, that makes sense. I just assumed i needed it. this saves me cash from my cache, lol.   so just use the older SSD until it get grumpy and then go without? 

[LIGISTX]

8 hours ago, Quozl said:

thank you so much, that makes sense. I just assumed i needed it. this saves me cash from my cache, lol.   so just use the older SSD until it get grumpy and then go without? 

Yup. Or just take it out now so it doesn’t cause an issues. A harddrive can saturate a gigabit LAN connection, so for media consumption only NAS, a cache more or less doesn’t matter. The cache would help if you are writing to the NAS a lot, from lots of sources, or if running lots of containers.
 

Streaming video content doesn’t matter what size the TV is, and doesn’t really matter what resolution the TV is…. The bitrate of the file is all that matters. Yes, a higher res file, if encoded with the same quality settings, would be more bitrate, but that’s the only thing that matters. To put this into perspective tho, a full 4k bluray, with Dolby vision HDR and Atmos is “only” about 80 mb/s. That’s 10 MB/s… your LAN is 125MB/s (gigabit is 125MB) and a harddrive can easily read faster than that. For a simple streaming box, none of this is a concern at all.