a technical IT blog
Archive for the ‘iSCSI’ Category.
Recently I was setting up DRBD (in short: “block devices designed as a building block to form high availability (HA) clusters”) between two data centers.
DRBD doesn’t apply any form of compression on the data that is replicated; is it a good idea to enable compression in the VPN link if you replicate your data with DRBD over Internet? Here is a quick test.
See Solving reliability and scalability problems with iSCSI, part 1 article.
The latest stable IET release, 0.4.15, suffers yet another misfeature: it will likely break all initiators when the ietd process is restarted (ietd restart, machine restart etc.).
This is because on ietd shutdown, the user space daemon is just killed, but it doesn’t have the corresponding signal handler and the kernel space module doesn’t perform any cleanups for it.
From initiator’s perspective, several things may happen:
Of course, no one wants to have the filesystem remounted read only, or to have the hard drive ripped off from a working system (this is how it looks from the perspective of the kernel if we loose a iSCSI connection).
There is a simple solution to that, although some may say it’s an ugly hack.
Continue reading ‘Solving reliability and scalability problems with iSCSI, part 2’ »
Because datacenters are very dependent on iSCSI, with an increasing amount of diskless servers booted directly off iSCSI NAS devices, a rock-solid operation of iSCSI is mandatory. The system should not fail even if the connection between iSCSI target and initiator is broken.
Continue reading ‘Solving reliability and scalability problems with iSCSI’ »