On Saturday, December 18, 2010 03:08:45 am Terry Barnaby wrote: > It is strange, however, how the system can run perfectly fine with good > fast disk IO for a while and then go into this slow mode. In the slow > mode a command can take 30seconds or more to run on an unloaded system. > It smacks of some Linux kernel SATA driver/RAID1 versus WD EARS drive > interaction to me. It's definitely something; the TLER discussions I've seen are just partial explanations at best. > However, I think I will change the drives. I was hoping to try some WD10EADS > ones I have, but after your issues I will look at the RE series or > another make ... The RE series is WD's 'RAID Enterprise' or 'RAID Enabled' (depending on how you look at it) drives, and cost more. They should work fine in RAID. The lower cost WD drives have been giving problems in RAID, and not just on Linux. WD even says they are not designed for RAID. Please see the responses at: http://community.wdc.com/t5/Other-Internal-Drives/1-TB-WD10EARS-desynch-issues-in-RAID/m-p/11559 Also see: http://wdc.custhelp.com/cgi-bin/wdc.cfg/php/enduser/std_adp.php?p_faqid=1397 That last link is to WD's FAQ; it explains the root cause of the issue, that of deep cycle recovery (saying point blank that the drive could take *2* *minutes* to recover *one* *sector* in error). So basically any time the drive hits an error, things slow to a crawl as the iowaits pile up. This is the info iostat -x 1 will give you; watch the await time (given in milliseconds); I saw awaits of up to 20,000 ms while trying to use my WD15EADS drive in RAID1. -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
