A nice and informative note about how to obtain OracleASM attributes, including “hidden attributes” can be found here. Including the special attribute “_rebalance_compact” which affects the post-rebalance ‘compact’ ASM operation, when altering DiskGroups (per-DiskGroup, of course). Just a reminder about this specific attribute – when ASM performs rebalance operation (adding or dropping disks) it attempts…
The IO scheduler blk_mq was designed to increase disk performance – better IOps and lower latency – on flash disk systems, with emphasis on NVME devices. A nice by-product, is that it increases performance on the “older” SCSI/SAS/SATA layer as well, when the disks in the back are SSD, and even when they are rotational…
Every Linux admin is familiar with the long time running through a large directory tree (with hundred of thousands of files and more) can take. Most are aware that if you re-run the same run-through, it will be shorter. This is caused by a short-valid filesystem cache, where the memory is allocated to other tasks,…
All ZFS users are familiar with ‘zpool iostat’ command, however, it is not easily translated into Linux ‘iostat’ command. Using large pools with many disks will result in a mess, where it’s hard to identify which disk is which, and going to a translation table from time to time, to identify a suspect slow disk….
This is a tricky one. In order to resize /boot, which is, commonly the first partition, you need to push forward the beginning of the next partition. This is not an easy task, especially if you are not using LVM – then you have to use external partitioning modification tools, like PQMagic (if it still…
You can find bazillion sites explaining Linux LVM, however, I am preparing for my next article, about partition resize for the advanced user, and LVM deep understanding is required, so I have decided to explain some of the internals of LVM for the advanced user. This explains the how it is built more than the…
