The ext3 filesystem supports write barriers which are designed to allow a filesystem to take advantage of a disk’s write cache without fear of compromising the ingetrity of the filesystem on a power failure or kernel panic. I’ve seen reports that ext3 write barriers have a significant impact on performance. Of course, the alternative is to disable the write cache (as is recommended many places) and suffer the performance loss from that. Given that the use of write barriers means forsaking many Linux storage tools which do not support write barriers (lvm, dmraid, dmcrypt, md raid except raid1, etc) it seems like the best option for flexibility is to just turn off the hard disks write cache and keep one’s options open. However, if the difference in performance between write barriers enabled and write cache disabled is significant then using write barriers would be a better option when IO performance is important. I often find IO to be the bottleneck on my servers so any improvement in IO performance is worth investigating. I ran some tests with bonnie++ and came up with these numbers.

I used to be a big fan of various wiping utilities such as DBAN and wipe. However, as hard disk capacities have grown much faster than hard disk speeds I’m feeling like elaborate wiping methods take too long to run. There has been some discussion as of late that fears about being able to recover data from a hard disk that had been overwritten were largely irrelevant with modern hard disk technology. I think the solution is to use encrypted disks by default whenever possible and to wipe disks by simply zeroing them. I took a 400GB disk and zeroed it yesterday and the process took somewhere between 5 and 6 hours to complete and that’s just for 1 pass of writing zeros. The idea of multiple passes using random data means at least a day’s worth of effort if not more depending on the number of passes. Although I could setup an old PC in my basement to take on the task I’m not sure it’s worth the money spent on the electricity. So I will practice using the dd if=/dev/zero method of wiping disks for now.

I've been quite happy with my purchases of Seagate's 7200.11 drives. The 640GB and 750GB are quite cheap and the 1.5TB makes a great external drive. I've replaced my 2 500GB external drives with a 1.5TB drive so that I can have 1 drive for the sake of simplicity. The 640GB drive is a 2 platter design and I suspect that the 750GB is always a 3 platter despite Seagate having the tech for 375GB platters for the 4 platter 1.5TB. Given my experience with drives with 1 year warranties failing within 2 years I'm pleased that Seagate offers a 5 year warranty on all of these drives. The only other drive I will be purchasing in the near future is the Western Digital RE3 for servers. The multiuser performance of the RE3 is somewhat above the 7200.11. However, the 7200.11 has performed quite well in my tests and I'm also impressed by it's low noise and low temperature.