Here are some basic things to do when debugging storage performance problems on Linux. It’s deliberately not an advanced guide, I might write about more advanced things in a later post.
When a hard drive is failing it often has to read sectors several times to get the right data, this can dramatically […]
I’m installing new 4TB disks on an older Dell server, it’s a PowerEdge T110 with a G6950 CPU so it’s not really old, but it’s a couple of generations behind the latest Dell servers.
I tried to enable UEFI booting, but when I turned that option on the system locked up during the BIOS process […]
I wrote a BTRFS status report yesterday commenting on the uneventful use of BTRFS recently .
Early this morning the server that stores my email (which had 93 days uptime) had a filesystem related problem. The root filesystem became read-only and then the kernel message log filled with unrelated messages so there was no record […]
My last BTRFS status report was in April , it wasn’t the most positive report with data corruption and system hangs. Hacker News has a brief discussion of BTRFS which includes the statement “Russell Coker’s reports of his experiences with BTRFS give me the screaming heebie-jeebies, no matter how up-beat and positive he stays about […]
I’ve just had to do yet another backup/format/restore operation on my workstation due to a BTRFS corruption problem, but as usual I didn’t lose any data. The BTRFS data integrity features work reasonably well even when the filesystem gets into a state where the kernel will only accept a read-only mount.
Given that the BTRFS […]
For some years LVM (the Linux Logical Volume Manager) has been used in most Linux systems. LVM allows one or more storage devices (either disks, partitions, or RAID sets) to be assigned to a Volume Group (VG) some of which can then allocated to a Logical Volume (LVs) which are equivalent to any other block […]
I’ve seen many comments about swap space and SSD claiming that swap will inherently destroy SSD through using too many writes. The latest was in the comments of my post about swap space and SSD performance . Note that I’m not criticising the person who commented on my blog, everyone has heard lots of reports […]
Since my blog post about BTRFS in March  not much has changed for me. Until yesterday I was using 3.13 kernels on all my systems and dealing with the occasional kmail index file corruption problem.
Yesterday my main workstation ran out of disk space and went read-only. I started a BTRFS balance which didn’t […]
In 2007 I wrote a blog post about swap space . The main point of that article was to debunk the claim that Linux needs a swap space twice as large as main memory (in summary such advice is based on BSD Unix systems and has never applied to Linux and that most storage devices […]
There is a BTRFS bug in kernel 3.13 which is triggered by Kmail and causes Kmail index files to become seriously corrupt. Another bug in BTRFS causes a kernel GPF when an application tries to read such a file, that results in a SEGV being sent to the application. After that the kernel ceases to […]