Raid 10 sounds good, but the answers are still depending on which database, how large are the files and which kind of i/o....
Raid 6 is a raid 5 with a double parity algorithm => means one write operation more (but not for writing your data.. :-) ) Raid 10 surely offers a better read performance. For a 4 Disk configuration I think raid 10 is the best choice. If you don't have the recommendations from your database provider you need to test where you get the best performance. The Perc has an internal Cache - means your data can be cached before they are written on the disk and read out of the disks. For read => it is read ahead/adaptive read ahead For write it is write back => in these situations the controller cache your data before they are written on the disk. The Cache from the controller is battery protected in cases of power loss. If you enable the disk cache too => your data are cached twice => this can result in both => better and slower performance => all is dependent on your i/o's. Random or sequential..... Note: the disk cache isn't write protected => in cases of power loss the data is lost and can result in an inconsistent database.... -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of John G. Heim Sent: Monday, April 26, 2010 10:29 PM To: linux-poweredge-Lists Subject: Howto configure PERC for blind/vi Last week I asked if there was an accessible way to configure a PERC (accessible to the blind that is). Well, I have managed to boot from a grml CD, get speech started, and install the dellomsa debian port. To install the dellomsa port, you'd have to update the sources.listt file, then do an 'apt-get update' and 'apt-get install dellomsa'. I still intend to make a modified grml disk with dellomsa already installed. But don't hold your breath. [Probably no other blind people on this list anyway.) So now I can do a 'omreport storage vdisk'. The results are below. It looks as if Dell has already configured the RAID for me. My only remaining question is whether the below configuration is optimal for a database server. It says /dev/sda is RAID 1. That will be the OS. But /dev/sdb is RAID10. People here were recommending RAID 6. Should I change it? What about the other settings like read policy, write policy, and cache policy? List of Virtual Disks in the System Controller PERC 6/i Integrated (Embedded) ID : 0 Status : Ok Name : Virtual Disk 0 State : Ready Progress : Not Applicable Layout : RAID-1 Size : 136.13 GB (146163105792 bytes) Device Name : /dev/sda Type : SAS Read Policy : No Read Ahead Write Policy : Write Back Cache Policy : Not Applicable Stripe Element Size : 64 KB Disk Cache Policy : Disabled ID : 1 Status : Ok Name : Virtual Disk 1 State : Ready Progress : Not Applicable Layout : RAID-10 Size : 272.25 GB (292326211584 bytes) Device Name : /dev/sdb Type : SAS Read Policy : No Read Ahead Write Policy : Write Back Cache Policy : Not Applicable Stripe Element Size : 64 KB Disk Cache Policy : Disabled _______________________________________________ Linux-PowerEdge mailing list [email protected] https://lists.us.dell.com/mailman/listinfo/linux-poweredge Please read the FAQ at http://lists.us.dell.com/faq _______________________________________________ Linux-PowerEdge mailing list [email protected] https://lists.us.dell.com/mailman/listinfo/linux-poweredge Please read the FAQ at http://lists.us.dell.com/faq
