#block-device

Fixed: Seeking distributed, fault-tolerant, networked block storage #development #it #dev

Seeking distributed, fault-tolerant, networked block storage

I’m looking for a distributed, fault-tolerant network storage system which exposes block devices (not filesystems) on the clients.

A client’s block device should write simultaneously to several storage nodes

A client’s block device should not fail as long as not all storage nodes backing it went down

The master should automatically…

Fixed: Intentionally cause an I/O error in Linux? #solution #development #computers

Intentionally cause an I/O error in Linux?

Is there anyway, with Linux, to purposely cause a block device to report an I/O error, or possibly simulate one for testing purposes?

Answer [by Dennis Kaarsemaker]: Intentionally cause an I/O error in Linux?

Depends on what you want to test. Using an LD_PRELOADed library, you can trick applications into thinking things like ‘all writes fail with ENOSPC

Answer: Xen 4.1 host (dom0) with blktap disks ("tap:aio:") not connecting #computers #development #answer

Xen 4.1 host (dom0) with blktap disks ("tap:aio:") not connecting

Problem using blktap with xen-4.1 running Ubuntu Precise stock kernel with dom0 xen-4.1.

I get:

[ 5.580106] XENBUS: Waiting for devices to initialise: 295s...290s. ... [ 300.580288] XENBUS: Timeout connecting to device: device/vbd/51713 (local state 3, remote state 1)

And some syslog lines:

May 17 13:07:30 localhost logger:…

Solution: Is DRBD the only viable block replication solution for Linux? #it #development #fix

Is DRBD the only viable block replication solution for Linux?

I’ve found myself needing redundant storage at a block level. File-level replication (Gluster, GFS, etc) does not work for my use case.

It looks like DRBD is the go-to solution for block replication. There don’t seem to be too many other sane options. Have I failed in my research, or is DRBD the only game in town?

Answer [by Oliver]:…

Resolved: Readahead Settings for LVM, Device-Mapper, Software Raid and Block Devices – what wins? #fix #computers #answer

Readahead Settings for LVM, Device-Mapper, Software Raid and Block Devices – what wins?

I’ve been trying to find a straight answer on this one, and it has proved elusive. This question and its answer is close, but does not really give me the specifics I would like. Let’s start with what I think I know.

If you have a standard block device and you run sudo blockdev reportyou will get something…

How to: Readahead Settings for LVM, Device-Mapper, Software Raid and Block Devices – what wins? #dev #development #computers

Readahead Settings for LVM, Device-Mapper, Software Raid and Block Devices – what wins?

I’ve been trying to find a straight answer on this one, and it has proved elusive. This question and its answer is close, but does not really give me the specifics I would like. Let’s start with what I think I know.

If you have a standard block device and you run sudo blockdev reportyou will get something…