On Thu, 24 Jul 2008 10:20:31 John Andersen wrote: [...snip...]
Hmmm; last time I saw him my doctor said he thought I was still sane, yet I'm using raid0 for exactly that purpose...
Actually, I mis-spoke. I'm not using Raid 0 (which is data striping and is used to increase performance by spreading the i/o across multiple interfaces and take advantage of parallel read/writes), but linear raid which is different and concatenates multiple partitions into a single logical volume a-la LVM (but managed differently as I understand).
[...] Don't assume from the fact that you have not YET had a failure on raid0 that it is any safer than LVM. Its about the same risk. Loss of any of one of the partitions may cause loss of ALL data.
Depending on what file system you format the raid0 with it could be really serious to just have a couple sectors go bad.
Raid0 composed of 3 drives TRIPLES you chance of loss, because a fault on any ONE drive may render the whole thing borken. If you had a 1 in 10000 chance of a drive failure previously, you now have a 3 in 10000 chance.
Really, If I had three drives of approximately the same size, I would accept 2 drives worth of storage and sacrifice the other drive to the gods of Raid5.
Unfortunately they are 3 partitions spread across 2 physical drives (2 on /dev/sda, on one /dev/sdb) that are not even approximately the same size. I just recently replaced a 150GB drive with a 640GB unit; the 250GB drive that was previously the boot drive was moved to the secondary interface. To avoid reinstalling I simply dd'd the 250GB drive to the 640GB drive, then repartitioned/reformatted the 250GB drive. In doing so I created a new 200GB /home partition as Raid 1 mirrored on both drives. I also relocated a couple of other partitions on the larger drive (so that I could make them bigger) but that left me with three non-contiguous partitions (1x 100GB, 1x 42GB and 1 around 85GB) that I figured would be much more useful as one large partition around 220GB, hence the use of linear raid to concat them together. Yes, I know that it is not ideal but the data stored on there is non-critical and if it does disappear, I'm not going to lose much sleep over it. The critical stuff is all on a mirrored volume and backed up externally. Eventually I'll replace the 250GB unit with another 640GB unit and then I'll review the partitioning strategy. Regards, -- =================================================== Rodney Baker VK5ZTV rodney.baker@iinet.net.au =================================================== A hypothetical paradox: What would happen in a battle between an Enterprise security team, who always get killed soon after appearing, and a squad of Imperial Stormtroopers, who can't hit the broad side of a planet? -- Tom Galloway