The larger the parity stripe is, the longer it takes to do writes. This is why for performance for most raid controllers and SANs the sweetspot is around 7 drives in a raid 5 or raid 6. If you go beyond that, read performance may still increase, but the write performance starts degrading faster, which reduces overall performance. I can't tell you how long it'll take to reconfigure a setup like yours, but it doesn't surprise me the least bit that it's taking more than 4 days. I will be somewhat surprised if it's done in less than 7 days. Note that a rebuild from replacing a failed drive will also probably take 24+ hours (during which you'll be taking a potentially significant performance hit). This is also the result of using such a large raid stripe.
Hello All, I'm in the process of doing an online RAID level migration on an H700 in an R510 from what was a RAID5 with a dedicated hot spare (11x2TB + 1x2TB) to a RAID6 (12x2TB). Unassigning the hot spare and starting the migration went fine. However, I wasn't expecting the cache policy to change to disabled and my write performance to the virtual disk has consequently dropped to about 8.8MB/s. I thought I could live with that for a short while but four days later the migration is only 29% through. That would appear to give a 13 day total migration time. Is there anything I can do to speed this up, eg increase the priority of the migration? The OS is Centos5.8 (a RHEL clone) and the migration was kicked off through the OpenManage web app. Thanks, Jon
H700 RAID level migration performance