Bill Davidsen wrote: > Robin Bowes wrote: >> Bill Davidsen wrote: >> >>> There have been several recent threads on the list regarding software >>> RAID-5 performance. The reference might be updated to reflect the poor >>> write performance of RAID-5 until/unless significant tuning is done. >>> Read that as tuning obscure parameters and throwing a lot of memory into >>> stripe cache. The reasons for hardware RAID should include "performance >>> of RAID-5 writes is usually much better than software RAID-5 with >>> default tuning. >>> >> >> Could you point me at a source of documentation describing how to >> perform such tuning? >> > No. There has been a lot of discussion of this topic on this list, and a > trip through the archives of the last 60 days or so will let you pull > out a number of tuning tips which allow very good performance. My > concern was writing large blocks of data, 1MB per write, to RAID-5, and > didn't involve the overhead of small blocks at all, that leads through > other code and behavior. Actually Bill, I'm running RAID6 (my mistake for not mentioning it explicitly before) - I found some material relating to RAID5 but nothing on RAID6. Are the concepts similar, or is RAID6 a different beast altogether? >> Specifically, I have 8x500GB WD STAT drives on a Supermicro PCI-X 8-port >> SATA card configured as a single RAID6 array (~3TB available space) >> > No hot spare(s)? I'm running RAID6 instead of RAID5+1 - I've had a couple of instances where a drive has failed in a RAID5+1 array and a second has failed during the rebuild after the hot-spare had kicked in. R. - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
