On Mon, Jun 3, 2024 at 11:17 AM Dale <rdalek1...@gmail.com> wrote: > > When you say HBA. Is this what you mean? > > https://www.ebay.com/itm/125486868824 >
Yes. Typically they have mini-SAS interfaces, and you can get a breakout cable that will attach one of those to 4x SATA ports. Some things to keep in mind when shopping for HBAs: 1. Check for linux compatibility. Not every card has great support. 2. Flashing the firmware may require windows, and this may be necessary to switch a card between RAID mode and IT mode, the latter being what you almost certainly want, and the former being what most enterprise admins tend to have them flashed as. IT mode basically exposes all the drives that are attached as a bunch of standalone drivers, while RAID mode will just expose a limited number of virtual interfaces and the card bundles the disks into arrays (and if the card dies, good luck ever reading those disks again until you reformat them). 3. Be aware they often use a ton of power. 4. Take note of internal vs external ports. You can get either. They need different cables, and if your disks are inside the case having the ports on the outside isn't technically a show-stopper but isn't exactly convenient. 5. Take note of the interface speed and size. The card you linked is (I think) an 8x v2 card. PCIe will auto-negotiate down, so if you plug that card into your v4 4x slot it will run at v2 4x, which is 2GB/s bandwidth. That's half of what it is capable of, but probably not a big issue. If you want to plug 16 enterprise SSDs into it then you'll definitely hit the PCIe bottleneck, but if you plug 16 consumer 7200RPM HDDs into it you're only going to hit 2GB/s under fairly ideal circumstances, and with fewer HDDs you couldn't hit it at all. If you pay more you'll get a newer PCIe revision, which means more bandwidth for a given number of lanes. 6. Check for hardware compatibility too. Stuff from 1st parties like Dell/etc might be fussy about wanting to be in a Dell server with weird firmware interactions with the motherboard. A 3rd party card like LSI probably is less of an issue here, but check. Honestly, part of why I went the distributed filesystem route (Ceph these days) is to avoid dealing with this sort of nonsense. Granted, now I'm looking to use more NVMe and if you want high capacity NVMe that tends to mean U.2, and dealing with bifurcation and PCIe switches, and just a different sort of nonsense.... -- Rich
