Corporate procurement policies

Hardware choice may be constrained by organizational policy. Perhaps your company enjoys a volume discount from HP, or has an umbrella support contract with IBM. You may even work for a company that sells servers and are thus urged or compelled to keep it in the family, dogfood style: https://en.wikipedia.org/wiki/Eating_your_own_dog_food.

In most cases, this will not crimp your Ceph-stacking style substantially, though this author has seen three problematic instances.

• On occasion, procurement policies are so draconian that it is nearly impossible to order a custom hardware configuration, with the only choices a small handful of ill-fitting models on an anachronistic menu, for example, a 1U chassis with only 4 x 300 GB LFF drives. Situations such as this are fortunately rare, but you must weigh how creative you can be with the options provided against the difficulty of escalating to source a configuration that makes sense. One strategy might be to order a bare-bones chassis and add appropriate drives and adapters as additional line items.

• Another was a division compelled to use only a certain brand of servers, without the ability to add even out-of-sight these internal third-party components. This resulted in an initial architecture using co-located journals (see Chapter 2, Ceph Components and Services) on Large Form Factor (LFF) rotating disks. Aggregate cluster performance was cut in half right from the start, and the intense seek pattern tickled a flaw in one manufacturer's firmware, resulting in frequent read errors. Remediation costs far more in service degradation, engineer time, and drive replacement than lobbying for appropriate third-party components up front would have.
• A major customer of another division within the company suddenly in-sourced, abandoning nearly three thousand servers with considerable time left on their leases. Other business units were compelled to take over these one- to two-generation old systems, with small and tired HDDs, instead of buying new ones.

Consider carefully your compromises in these areas, as they set precedents and may be difficult, expensive, or impossible to recover from when unsuitable gear is deployed.