What is DRBD

What is DRBD

 

DRBD is a block device which is designed to build high availability clusters. This is done by mirroring a whole block device via (a dedicated) network. You could see it as a network raid-1.

 

DRBD is copyright by Philipp Reisner, Lars Ellenberg and LinBit.

 

What is the scope of drbd, what else do I need to build a HA cluster?

 

DRBD takes over the data, writes it to the local disk and sends it to the other host. On the other host, it takes it to the disk there.

 

The other components needed are a cluster membership service, which is supposed to be heartbeat, and some kind of application that works on top of a block device.

 

Examples:

A filesystem & fsck.

A journaling FS.

A database with recovery capabilities.

 

http://www.drbd.org/

 

Maxtor OneTouch external hard drive with a MacBook

First of all, this is the product:

http://www.maxtorsolutions.com/en/catalog/OTIII_Turbo/index.html

Oddly, it doesn’t appear under: Office and Business
but does under Creative Pros:

http://www.maxtorsolutions.com/en/Main/creative_pros.html

There are several differences between this and the other One Touch systems.

1. This offers RAID (both striping, for disk performance, and mirroring, for secure backups).

2. It has two large disks giving 1.5TB (or 750GB if mirroring)

3. It has Firewire 800 which is superfast. The MacBook doesn’t support Firewire 800 but the MacBook Pro or desktop do which is handy if you ever decide to upgrade.

OK, the down-sides.

1. The Disk Manager tool doesn’t work properly under Leopard (it won’t let you manage the RAID settings) which means if you want disk mirroring you having to install the Manager tool on a Windows machine to change the RAID settings as it is set up to do Striping by default. A pain and odd given that the disk is very Mac friendly – e.g. the disk is Mac formatted and the first section in the user guide is aimed at Mac users as opposed to PC users.

Handy links:

Topic : MLeopard and MAXTOR one Touch III 350Gb external Hardisk http://discussions.apple.com/thread.jspa?threadID=1209889&tstart=0

Maxtor OneTouch III Family
http://www.seagate.com/www/en-us/support/installation_assistance/installation_instructions/external_drives_&_personal_servers/ot3

Seagate/Maxtor External (and/or Network) Storage Compatibility Issues with Mac OS X 10.5 (Leopard)
http://seagate.custhelp.com/cgi-bin/seagate.cfg/php/enduser/std_adp.php?p_faqid=4975&p_created=1193688733&p_sid=HYgybLVi&p_accessibility=0&p_redirect=&p_lva=2223&p_sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3Jvd19jbnQ9MiwyJnBfcHJvZHM9NDEwLDQyMSw0NjEsNDY1JnBfY2F0cz0wJnBfcHY9NC40NjUmcF9jdj0mcF9zZWFyY2hfdHlwZT1hbnN3ZXJzLnNlYXJjaF9ubCZwX3BhZ2U9MSZwX3NlYXJjaF90ZXh0PWxlb3BhcmQ*&p_li=&p_topview=1

MacOSX Compact Sparse Image…

One useful OS X feature is the ability to create disk images. A disk image is a single file that, when double-clicked, appears like a typical hard drive to the operating system. (Most software you download comes on a disk image.) Disk images a great way to store related files that you don’t need to use often, as they can be “out of sight” until you need them. They’re also useful if you want to store something securely, as you can create encrypted disk images that require a password to mount.

There are essentially two types of disk images—a normal disk image and a sparse disk image. With a normal disk image, the disk image will consume as much drive space as its size, even when empty—i.e. a 40MB normal disk image requires 40MB of drive space, even if you’ve never used it. Sparse disk images, on the other hand, are disk image files that require just as much space as their contents require. So a 40MB sparse disk image will only need 40MB of drive space if you’ve saved 40MB of data onto it. The disk image will grow automatically as space is required.

What isn’t so obvious is that a sparse image won’t shrink automatically. Check out the link for a handy article on how to compact a sparse image.

http://www.macworld.com/weblogs/macosxhints/2007/06/compactsparse/index.php

MacOSX Compact Sparse Image…

One useful OS X feature is the ability to create disk images. A disk image is a single file that, when double-clicked, appears like a typical hard drive to the operating system. (Most software you download comes on a disk image.) Disk images a great way to store related files that you don’t need to use often, as they can be “out of sight” until you need them. They’re also useful if you want to store something securely, as you can create encrypted disk images that require a password to mount.

There are essentially two types of disk images—a normal disk image and a sparse disk image. With a normal disk image, the disk image will consume as much drive space as its size, even when empty—i.e. a 40MB normal disk image requires 40MB of drive space, even if you’ve never used it. Sparse disk images, on the other hand, are disk image files that require just as much space as their contents require. So a 40MB sparse disk image will only need 40MB of drive space if you’ve saved 40MB of data onto it. The disk image will grow automatically as space is required.

What isn’t so obvious is that a sparse image won’t shrink automatically. Check out the link for a handy article on how to compact a sparse image.

http://www.macworld.com/weblogs/macosxhints/2007/06/compactsparse/index.php

EyeTV – can’t record the live buffer – shame!

There is one feature I think is missing from EyeTV though, has got to do with recording and time-shifting. EyeTV always keeps a buffer of a few minutes, so you can rewind live TV incase you missed something. Very handy for when something happens quickly or you swore you saw something but didn’t’ believe it. However, you can’t record what’s in this buffer to save it for later, which is what you usually want to do if something weird/funny/odd happens. I’m sure the boffins at Elgato are working hard on integrating it into EyeTV 3.

http://forums.mactalk.com.au/showthread.php?t=25496