I’m syncoiding from my normal RAIDz2 to a backup mirror made of 2 disks. I looked at zpool iostat and I noticed that one of the disks consistently shows less than half the write IOPS of the other:

                                        capacity     operations     bandwidth 
pool                                  alloc   free   read  write   read  write
------------------------------------  -----  -----  -----  -----  -----  -----
storage-volume-backup                 5.03T  11.3T      0    867      0   330M
  mirror-0                            5.03T  11.3T      0    867      0   330M
    wwn-0x5000c500e8736faf                -      -      0    212      0   164M
    wwn-0x5000c500e8737337                -      -      0    654      0   165M

This is also evident in iostat:

     f/s f_await  aqu-sz  %util Device
    0.00    0.00    3.48  46.2% sda
    0.00    0.00    8.10  99.7% sdb

The difference is also evident in the temperatures of the disks. The busier disk is 4 degrees warmer than the other. The disks are identical on paper and bought at the same time.

Is this behaviour expected?

  • @DecronymAB
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    7 days ago

    Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I’ve seen in this thread:

    Fewer Letters More Letters
    NVMe Non-Volatile Memory Express interface for mass storage
    PCIe Peripheral Component Interconnect Express
    PSU Power Supply Unit
    SATA Serial AT Attachment interface for mass storage
    SSD Solid State Drive mass storage
    ZFS Solaris/Linux filesystem focusing on data integrity

    6 acronyms in this thread; the most compressed thread commented on today has 7 acronyms.

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