Hard drives with different cache sizes?

[f8340fidsolfwhf20]

I have a FreeNAS box I've been using for a few years now that has 3 of the drives linked below in RAIDZ1:
(HGST DeckStar NAS 3.5" 4TB 7200 RPM 64MB Cache Drive)
https://www.newegg.com/Product/Product.aspx?Item=9SIA2W04177421

I went to buy another one of these drives so I could rebuild my pool as RAIDZ2, however Newegg's third-party seller shipped me this one instead:
(HGST DeckStar NAS 3.5" 4TB 7200 RPM 128MB Cache Drive)
https://www.newegg.com/Product/Product.aspx?Item=N82E16822146116

The only conceivable difference I can see between the two is that the ones I own have a 64 MB cache while the one I received has a 128 MB cache. I've searched around the forums/online and found plenty of posts about different brands/sizes of hard drives, but no mention of whether having the same brand/size hard drives with different cache sizes will work/cause issues. Anyone have any knowledge/experience with mixing cache sizes in a ZFS pool? Thank you!

 

[MatthewSteinhoff]

Don't worry. It'll be fine.

Cheers,
Matt

 

[DrKK]

Probably the worst that will happen is your 128MB cache drive will behave as if it's a 64MB cache drive, for all intents and purposes. i.e., no adverse effect. Proceed sir.

 

[Chris Moore]

I have a FreeNAS box I've been using for a few years now that has 3 of the drives linked below in RAIDZ1:
(HGST DeckStar NAS 3.5" 4TB 7200 RPM 64MB Cache Drive)
https://www.newegg.com/Product/Product.aspx?Item=9SIA2W04177421

I went to buy another one of these drives so I could rebuild my pool as RAIDZ2, however Newegg's third-party seller shipped me this one instead:
(HGST DeckStar NAS 3.5" 4TB 7200 RPM 128MB Cache Drive)
https://www.newegg.com/Product/Product.aspx?Item=N82E16822146116

The only conceivable difference I can see between the two is that the ones I own have a 64 MB cache while the one I received has a 128 MB cache. I've searched around the forums/online and found plenty of posts about different brands/sizes of hard drives, but no mention of whether having the same brand/size hard drives with different cache sizes will work/cause issues. Anyone have any knowledge/experience with mixing cache sizes in a ZFS pool? Thank you!

A few years ago, I built a NAS using all second hand drives sourced from eBay. I had all brands and models in there, WD Black, Seagate Desktop, HGST, even Toshiba. Twelve drives and at most only two that were the same. Different rotational speed, different cache, it was a total mixed lot.
The point is, it all worked fine. The only problem I had was because they started out as old drives to begin with, they didn't last me long before I started getting bad sectors but that (I feel certain) had nothing to do with being a mixed up bag as much as it had to do with the fact that they were already old when I got them. Still, it lasted me a couple years until I could afford to buy all new drives.

 

[MatthewSteinhoff]

We, too, use a mixed batch of drives, Chris.

When we order desktops, they come with 2TB conventional drives. We pull those and replace them with 256GB SSDs. We then take the 2TB drives and toss them into FreeNAS. We don't even bother to test them first. They are so plentiful and FreeNAS is so resilient, we just toss them into the enclosure and let them run. None have lasted for less than a year. Some were two years old when we put them in FreeNAS and are going on four years of use now.

(I'm not suggesting that as a best practice. That's just what we do.)

Cheers,
Matt

 

[Chris Moore]

I'm not suggesting that as a best practice. That's just what we do.

I don't know, I think it is a good idea. Next time we order systems at work, I think I might just do this...

 

[Ericloewe]

Different cache sizes are way down my list of concerns, somewhere below "vat of sulfuric acid mysteriously brought into office and spilled over the server" and "Godzilla fighting Mothra shuts down HDD production plant and sends drive prices skyrocketing".

 

[f8340fidsolfwhf20]

Glad to know my concerns were unwarranted :) thanks everybody!