Electronics with passion: amplifiers and power supplies, FET's and vacuum tubes..

Month: January 2011

Silent computer: DIY leather suspension for 3.5″ HDD

Recently I got myself couple of cool big CoolMaster computer cases. Anodised aluminium, plexiglas side panel and convenient block of USB-Sound-ESATA connectors... Being very pragmatic about computers I anyhow moved my current machinery into the new temples. The main goal of this move was to make them QUIET. Indeed, the monster cases had huge (read silent) fans, plenty of space for proper heat-sinking and arranging the air-flow. I even decided to glue some dumping material on that enormous back-cover. The day passed, everything has settled well and the machines ran much, much quieter than it was before. Till I sat to work a bit at night. There was that endless "RRR" sound. Not very loud, but it was something new in comparison to the old clunky sharp-edged iron boxes. Perhaps this "new" sound was always there and simply masked by the old little fans hissing aloud. Who knows, but that night it was unbearable. I soon realised the "RRR" was about 120Hz. No need to measure the frequency - you guess it quickly: that was the beat of 7200RPM hard drives. Most probably the big case made much better low frequency resonant chamber for them.

I did a quick marketing research,

S/W RAID resync’ing all the time

Ever wondered why the heck mdadm & Co did not complain about failing drives, but the system was sluggish and blinked HDD activity LEDs as crazy? That's how it looked in my case: [root@lemon ~]# cat /proc/mdstat Personalities : [raid10] [raid6] [raid5] [raid4] md5 : active raid5 sda3[0] sdb3[1] sdc3[2] sdd3[3]      5809906944 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU]      [============>........]  resync = 63.2% (1224003712/1936635648) finish=2185.5min speed=5432K/sec      bitmap: 1/231 pages [4KB], 4096KB chunk I was observing this very often, thinking that one of my new drives went wonky already. Not to worry about: it was simply the kernel that did not display checking correctly, instead it wrote resync. The following commands will reveal the real info about