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1 vote

Simulate slow disks in KVM to see effect of LVM cache in test setup

I decided to try out Austin Hemmelgarn's method, and I can say definitively that it works... almost too well. I wanted to run a quick test with the Fedora 40 Workstation VM I already have installed, ...
FeRD's user avatar
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5 votes

Simulate slow disks in KVM to see effect of LVM cache in test setup

QEMU provides internal support for limiting bandwidth in bytes per second and IO rates based on IO operations per second (in both cases with support for doing this differently for read or write ...
Austin Hemmelgarn's user avatar
1 vote

Remove lvm volumes after fresh Debian install

Use the fdisk utility to create a new partition table. This will wipe the old partitions along with the LVMs. Use sudo fdisk /dev/sda to make changes to the partitions in this drive, type p to print ...
GingerLinger's user avatar
1 vote

Remove lvm volumes after fresh Debian install

These were not actual volumes but just device mappers. Either way that caused commands to think the disk is in use. I've listed the device mapper entries with dmsetup info and then deleted them via e....
bibac's user avatar
  • 121
2 votes

Remove lvm volumes after fresh Debian install

Nothing here says they are in use somehow – they're just there. And just like say, partitions on an MS-DOS partitioned hard drive, they are detected. Neat, actually! Check the output of sudo vgs – you ...
Marcus Müller's user avatar
5 votes

Simulate slow disks in KVM to see effect of LVM cache in test setup

The device-mapper subsystem includes CONFIG_DM_DELAY, a device-mapper target that can be used to add delay to disk operations. The Debian 12 standard kernel includes it as a module. For example: ...
telcoM's user avatar
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7 votes

Simulate slow disks in KVM to see effect of LVM cache in test setup

Qemu has native support for Network Block Devices (NBD), --drive file=nbd://<host>[:<port>]/[<export>]. (you could also use nbd.ko in the guest itself). That's kind of useful, ...
Marcus Müller's user avatar
3 votes
Accepted

Linux LVM disk partitioning scheme for a server?

The structure is broadly correct. For a server I'd be looking at storage resilience through RAID (and quite possibly dual PSUs, dual NICs, UPS, etc. but that's hardware and pretty much off-topic here)....
Chris Davies's user avatar
1 vote

how to manipulate LVM partition size

Some filesystems can be both extended and shrunk non-destructively; unfortunately RHEL 8's default filesystem type is XFS, which can be extended even while in use just fine, but cannot be currently ...
telcoM's user avatar
  • 101k
0 votes

how to manipulate LVM partition size

Without reboot? Sure. Without unmounting the partitions? Can be tricky. (see How to shrink root filesystem without booting a livecd) The idea is this. To reduce one partition by 10GB: lvreduce --size -...
ptr's user avatar
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