SD Cards & Readers

Which dual-SD module fits your PowerEdge generation

Choose the module by server generation first, because Dell changed the design from one generation to the next: 12th- and 13th-generation servers use full-size SD cards, the 14th generation moved to a combined IDSDM and vFlash module with microSD cards, and the 15th generation kept a two-card IDSDM.

Blade servers use their own versions of the module, so match the M-series or MX blade model as well as the generation. Searching by Dell part number? Dell's 12th-, 13th- and 14th-generation dual-SD modules include the 6YFN5, PMR79 and RT6JG.

IDSDM or vFlash: what each card does

An IDSDM is a mirrored boot device for an embedded hypervisor, and vFlash is storage that belongs to iDRAC. Dell describes the dual SD module as providing failover for embedded hypervisors, and its 13th-generation module mirrors two cards in RAID-1. vFlash is a licensed iDRAC feature: the card holds up to 16 partitions that iDRAC can present to the server as a floppy, hard disk or CD/DVD drive for images and one-time boot, and because it uses FAT32, a single file is limited to 4GB.

When an IDSDM card fails

A mirrored IDSDM keeps the server booting on one card. Dell's IDSDM white paper explains that writes go to both cards and reads come from the active card, and that if the active card fails or is removed, the second card becomes active automatically; iDRAC then reports the module's redundancy as Lost rather than Full and shows each card as Active, Standby, Failed or Offline. The mirror is rebuilt only during BIOS POST, where the server offers to copy the surviving card onto the replacement, and Dell advises rebuilding as soon as possible. Dell also asks for the module to be serviced only with AC power removed, since it runs on auxiliary power and pulling a card from a powered server breaks the mirror.

Card rules to know before ordering

Put matching cards in both IDSDM slots: Dell's 13th-generation module places the secondary card in a MISMATCH state when it is slower or smaller than the primary, its white paper requires the secondary to have at least as many bytes as the primary for a rebuild, and Dell's R650 documentation asks for Dell-branded SD cards in IDSDM systems. On the R740, Dell notes that the IDSDM and vFlash slot is not hot-pluggable, so power the server down before changing the module.

BOSS, the M.2 boot option

BOSS is Dell's M.2 SSD boot card, offered from the 14th generation for servers that boot a full operating system rather than a hypervisor alone. Dell's R640 technical guide positions BOSS for exactly that case: an IDSDM-style dedicated boot device, but for a full OS. Compare the options in the Dell BOSS Card Guide or browse BOSS Controller Cards; iDRAC hardware is on Remote Access Cards, and all of these sit under Cards & Controllers.

Dell IDSDM questions

What happens when one SD card in an IDSDM fails?

The server keeps running on the other card. Dell's IDSDM white paper explains that both cards receive every write, that the second card becomes active automatically if the active card fails, and that iDRAC then shows the redundancy as Lost. Replace the failed card with one of at least the same capacity and speed, with AC power removed, and accept the rebuild Dell offers during the next BIOS POST.