Buyer beware—that 2TB-6TB “NAS” drive you’ve been eyeing might be SMR

Enlarge / Shingled Magnetic Recording drives-unlike this Los Angeles-class submarine-aren't on anybody's list of "Fast Attack" vessels. (credit: Michael Meilen / ETC Robert Gulini)

Storage vendors, including but reportedly not limited to Western Digital, have quietly begun shipping SMR (Shingled Magnetic Recording) disks in place of earlier CMR (Conventional Magnetic Recording) disks.

SMR is a technology that allows vendors to eke out higher storage densities, netting more TB capacity on the same number of platters-or fewer platters, for the same amount of TB.

Until recently, the technology has only been seen in very large disks, which were typically clearly marked as "archival". In addition to higher capacities, SMR is associated with much lower random I/O performance than CMR disks offer.

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