Mixing SAS Drives in the same array - Same brand/speed - different generation/cache


May 15, 2019
I have an array that is made up of 2TB Dell branded Seagate Constellations that simply refuses to die or.... even degrade.
I have the opportunity to grab another handful of Dell branded Constellations for literally nothing, but they are a generation older.
Current drives - Constellation ES.1 (7200RPM, SAS 6G, 64MB Cache)
New/old drives - Constellation ES (7200RPM, SAS 6G, 16MB Cache)

Would you mix these drives within the same array ? an existing array ? (SAS2108 based HW RAID5)
Could it be as easy as setting 'Disk Cache Policy' to DISABLED in MR Storage Manager ?
Am I about to introduce problems to my 'array that refuses to die' ?

The current array is made up of 8 drives and I am looking to expand it to 12.
(still SAS2108 based HW RAID5...perhaps RAID6 with additional drives)


As always, thanks in advance,


Well-Known Member
Mar 18, 2016
With hardware raid you should always disable the cache on hdds. (Default behavior on adaptec raid controllers)
Yes you can mix the drives (I have a fileserver with 14 hgst hdds and 2 toshiba hdds in the same array and no problemes, even when the toshibas have less platter with higher storage density)

To be honest I wouldn't use 8 year old, small hdds not even for free.
Have you thought about replacing them with newer, larger hdds or even ssds?


May 15, 2019
Fortunately everything that I keep hot is also backed up in cold storage, as this is simply part of my Plex Media Server Library, so nothing really mission critical.

I had planned to begin upgrading slowly to SSDs, but I simply can't justify the over $100+ CDN per TB....and still rising. For the same price today, it comes down to a 1TB (low end) SSD vs a 4TB Red+ or Ironwolf, so the choice for me, at this point is pretty clear.

I am planning a complete array replacement for some SATA 3TB Constellations that I have, that although a few years newer than the SAS 2TB Constellations, have suffered a much higher failure rate and are showing their age in comparison.