{
  "slug": "smr-persistent-cache",
  "term": "SMR persistent cache",
  "aliases": [
    "SMR media cache"
  ],
  "definition": "An SMR persistent cache is a nonvolatile staging area that holds updates before they are incorporated into their target shingled regions.",
  "note": "This is distinct from volatile write caching [zoned]. Skylight inferred separate limits for journal allocation, payload space and mapping entries on its tested drives; those inferred values are not specifications for other models [skylight]. The linked analysis provides synthetic resource arithmetic, not a device benchmark [analysis].",
  "status": "shipping",
  "advantages": [],
  "limitations": [
    {
      "text": "A capacity bound does not predict stall time, firmware cleaning thresholds or the cause of a failed command.",
      "citationIds": [
        "analysis"
      ]
    }
  ],
  "related": [
    "device-managed-smr",
    "garbage-collection-smr",
    "shingled-band"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "skylight",
      "title": "Aghayev and Desnoyers: Skylight, FAST 2015, sections 4.5-4.6",
      "url": "https://www.usenix.org/system/files/conference/fast15/fast15-paper-aghayev.pdf",
      "accessed": "2026-10-15"
    },
    {
      "id": "zoned",
      "title": "Zoned Storage: Shingled Magnetic Recording Hard Disks",
      "url": "https://zonedstorage.io/docs/introduction/smr",
      "accessed": "2026-10-15"
    },
    {
      "id": "analysis",
      "title": "Hesela: SMR stalls, cache limits and the errors SMART can miss",
      "url": "https://hesela.com/analyses/smr-drive-failure-signatures/",
      "accessed": "2026-10-15"
    }
  ],
  "updated": "2026-10-15"
}