David Christensen wrote: > On 1/11/24 05:50, Dan Ritter wrote: > > David Christensen wrote: > STFW the Dell PowerEdge 6850 (circa 2004) featured "hot plug" disk drives, > expansion slots, memory risers, power supplies, and system cooling fans: > > https://downloads.dell.com/manuals/all-products/esuprt_ser_stor_net/esuprt_poweredge/poweredge-6850_user%27s%20guide4_en-us.pdf > > > STFW dell.com today, I see servers with: > > * hot plug hard drives > * hot spare hard drives > * dual hot plug redundant power supplies > * dual hot plug fully redundant power supplies > * dual hot plug fault tolerant power supplies > * dual hot plug fault tolerant redundant power supplies.
Hot plug disks are easy -- SATA, SAS and NVMe U.2 interfaces are all specified so that the chassis manufacturer can arrange for data to be disconnected before power. This is nearly but not quite ubiquitous in rackmountable servers; somewhat rare in desktops. Hot plugged fans are extremely easy -- there's no data being stored and no state of any consequence. Arranging an easy disconnect mechanism is the maximum difficulty. Hot spare is more a property of the RAID management software. mdadm, btrfs and zfs all support marking a disk as 'spare' and not using it until another disk is marked as failing. Interestingly: all PCIe cards are nominally hot-pluggable. -dsr-
