Hot swap and hot spare revisited.

By -
There are three levels of hot-something hardware repair capability in a storage system
  1. cold swap
  2. hot swap
  3. hot spare

differing on two properties
  1. if a downtime is required to perform the repair
  2. if a human intervention is required

Hence, the levels break down as follows:
  1. Cold swap: both downtime and human intervention required
  2. Hot swap: human intervention is required but no downtime
  3. Hot spare: no downtime and no human intervention


The price of the system increases with the level of hotness, while the maintenance cost decreases. In certain applications, where the maintenance cost is high, it is cheaper to put in enough "hot spare" parts for the entire useful life of the system than to use a hot-swap and human intervention. While an unmanned spacecraft is the extreme example of the high-cost maintenance, we will probably see maintenance-free end-user systems soon after hard drive production finally comes back to proper rates.

Comments

Post a Comment

Popular posts from this blog

QNAP revisited

By Geek -
For reference, we were using QNAP TS-639 Pro with six WD20EADS disks. After about half a year of use, the web-interface was running slower, so that we needed to wait for several minutes to obtain the list of the disks. Gradually, we noted that the array performance decreased significantly. It seemed obvious to assume that one of the member disks has been dropped from the array and a RAID5 was working in the degraded mode. However, all the member disks were marked as GOOD in the web-interface. It was suspicious that LEDs on the disk bays indicating the state and activity of the disks were blinking unevenly. Logically, for RAID5 one should expect almost symmetric load on the disks, but in fact, one of the disk LED was blinking much more frequently. Once we had run the bad blocks check on this disk through the web-interface, the disk dropped from the array in less than half an hour and its bay LED turned red. At this point, the web-interface began to work properly again. The disk taken fr
Read more

APFS Data Recovery

By -
Apple File System, APFS for short, is a brand-new filesystem released in 2017. The goal is to replace HFS+ which has been in use on Apple computers since 1998. Formally released in late 2017, APFS filesystem began to be used by default on Apple computers running under MacOS High Sierra. Among the main features of APFS filesystem are 64-bit pointers allowing to address 2^56 blocks More accurate created/accesses/modification time measured in nanoseconds since 1970-01-01 Copy-on-write Sharing blocks between APFS volumes Native full-disk encryption We are happy to announce that now ReclaiMe data recovery software is capable of recovering data from APFS-formatted devices be it a USB thumb drive, or external hard drive, or internal SSD boot drive. You can download the latest build of ReclaiMe at www.ReclaiMe.com .
Read more