On Sun, Mar 07, 2010 at 03:10:18AM -0500, Guy Watkins wrote: > } -----Original Message----- > } From: Keld Simonsen [mailto:keld@xxxxxxxxxx] > } Sent: Sunday, March 07, 2010 3:07 AM > } To: Neil Brown > } Cc: Guy Watkins; 'Greg Freemyer'; 'Mark Knecht'; 'Linux-RAID' > } Subject: Re: What RAID type and why? > } > } On Sun, Mar 07, 2010 at 01:21:13PM +1100, Neil Brown wrote: > } > On Sat, 06 Mar 2010 18:17:44 -0500 > } > "Guy Watkins" <linux-raid@xxxxxxxxxxxxxxxx> wrote: > } > > } > > } > } > > } At a minimum I would build a 3-disk raid 6. raid 6 does a lot of > } i/o > } > > } which may be a problem. > } > > > } > > If he only needs 3 drives I would recommend RAID1. Can still loose 2 > } drives > } > > and you don't have the RAID6 I/O overhead. > } > > > } > > } > and as md/raid6 requires at least 4 drives, RAID1 is not just the best > } > solution to survive two failures on a 3-device array, it is the only > } solution. > } > } Raid10 can also do it. > } > } raid1 is in many ways obsolete and you should rather use raid10, > } which in my eyeys is just another way of doing the same conceptual thing > } as raid1. > } > } Best regards > } keld > > Are you sure RAID10 can loose 2 of 3 drives? I did not think it worked that > way. I thought RAID10 maintained 2 copies, not 3. But I have never used > RAID10. If you ask mdadm to do it, yes. Example: mdadm --create /dev/md3 --chunk=256 -R -l 10 -n 3 -p f3 /dev/sd[abc]1 the "-p f3" is the one that asks to have 3 copies. best regards keld -- 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
