I recently got myself a refurbished DL380pG8 with a 25 SFF bay.

The idea was to put CentOS7 on it and use is as storage device, mixing shared storage, possibly some iSCSI drives for a couple of virtual machines, and cold storage for files that need to be kept but are rarely accessed.

This decision was made hastily and I realized after the fact that the cold storage part would have been much cheaper had I gone with LFF drives.

I currently am committed to using SFF drives as they have already been purchased, but when the space runs out I will need to consider a few options, and I'd rather have this all lined up right now.

My idea is to add a P822 RAID controller to this server (2 internal SAS and 4 external SAS ports).

My questions are : 1) if I use a P822 raid controller on this server, will I be able to add external drives (think StorageWorks MSA60 or whatever makes sense at that time) that handles LFF, even though my server disks are SFF? In other words, can the P822 handles a mix of SFF and LFF? - I know the server itself can't - I also believe an individual RAID array cannot mix LFF and SFF...But I'm not trying to do that

2) Is it wiser to also put my on-server disks on the P822, or to use the P822 for external bays and keep the included P420i for the on-server 25 SFF disks, splitting the work? (knowing that the disks aren't very busy anyways, especially the external "cold-storage" ones)

  1. The physical form factor of your disks doesn't matter to the server.
    You can definitely mix LFF and SFF in the same RAID, and you can definitely add an MSA60 or D2600 (both 12-bay LFF enclosures) to the P822 controller.

  2. You already have the P420 set up with your internal disks, so there's no real reason to decommission it and move everything to the P822.
    In addition to the performance incentive, it's a slightly more resilient setup to use both.
    For example if the P822 were ever to fail, your server would still be running on the P420 (though you'd lose access to your external disks).

  • Thank you - I was pretty sure I could mix LFF and SFF, but I didn't know you could even make a single RAID10 array with a mix SFF/LFF drives. Not that I`ll do so, but it might help to get a global spare big enough for all drives regardless of form factor.
    – Mike
    Nov 29 '18 at 18:57

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