When upgrading PurityOS on a Pure Storage FlashArray, the upgrade package file (.ppkg) is heavily compressed but still quite large, typically ranging between 6GB and 12GB depending on the version. Often, Implementation Engineers use a USB flash drive to transfer these upgrade files directly to the array's controllers, especially in dark sites where network-based file transfers are restricted.
However, standard USB flash drives are usually formatted with the FAT32 file system to ensure broad compatibility across different operating systems. FAT32 has a strict maximum file size limit of 4GB. Because the single Purity .ppkg file exceeds this limitation, engineers must split it into smaller chunks (usually using the Linux split -b command, which generates sequential files with suffixes like aa, ab) before copying them to the USB drive.
Once the split files are successfully transferred into the /home/puresetup/ directory on the FlashArray controller, they must be properly reassembled into the original, functional .ppkg binary. Because Purity runs on a custom Linux kernel, standard Linux CLI utilities apply here. The correct and officially supported method to achieve this is using the cat (concatenate) command. By running cat with the wildcard * on the split file names, the system sequentially reads the chunks in alphabetical order and redirects ( > ) the binary output to recreate the single, unified .ppkg file. Using join, tar, or zip will either fail to execute or corrupt the binary package entirely.