Re: XFS sunit/swidth for raid10
On Fri, 23 Mar 2007, Peter Rabbitson wrote: > dean gaudet wrote: > > On Thu, 22 Mar 2007, Peter Rabbitson wrote: > > > > > dean gaudet wrote: > > > > On Thu, 22 Mar 2007, Peter Rabbitson wrote: > > > > > > > > > Hi, > > > > > How does one determine the XFS sunit and swidth sizes for a software > > > > > raid10 > > > > > with 3 copies? > > > > mkfs.xfs uses the GET_ARRAY_INFO ioctl to get the data it needs from > > > > software raid and select an appropriate sunit/swidth... > > > > > > > > although i'm not sure i agree entirely with its choice for raid10: > > > So do I, especially as it makes no checks for the amount of copies (3 in > > > my > > > case, not 2). > > > > > > > it probably doesn't matter. > > > This was essentially my question. For an array -pf3 -c1024 I get swidth = > > > 4 * > > > sunit = 4MiB. Is it about right and does it matter at all? > > > > how many drives? > > > > Sorry. 4 drives, 3 far copies (so any 2 drives can fail), 1M chunk. my mind continues to be blown by linux raid10. so that's like raid1 on 4 disks except the copies are offset by 1/4th of the disk? i think swidth = 4*sunit is the right config then -- 'cause a read of 4MiB will stride all 4 disks... -dean - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: XFS sunit/swidth for raid10
dean gaudet wrote: On Thu, 22 Mar 2007, Peter Rabbitson wrote: dean gaudet wrote: On Thu, 22 Mar 2007, Peter Rabbitson wrote: Hi, How does one determine the XFS sunit and swidth sizes for a software raid10 with 3 copies? mkfs.xfs uses the GET_ARRAY_INFO ioctl to get the data it needs from software raid and select an appropriate sunit/swidth... although i'm not sure i agree entirely with its choice for raid10: So do I, especially as it makes no checks for the amount of copies (3 in my case, not 2). it probably doesn't matter. This was essentially my question. For an array -pf3 -c1024 I get swidth = 4 * sunit = 4MiB. Is it about right and does it matter at all? how many drives? Sorry. 4 drives, 3 far copies (so any 2 drives can fail), 1M chunk. - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: XFS sunit/swidth for raid10
On Thu, 22 Mar 2007, Peter Rabbitson wrote: > dean gaudet wrote: > > On Thu, 22 Mar 2007, Peter Rabbitson wrote: > > > > > Hi, > > > How does one determine the XFS sunit and swidth sizes for a software > > > raid10 > > > with 3 copies? > > > > mkfs.xfs uses the GET_ARRAY_INFO ioctl to get the data it needs from > > software raid and select an appropriate sunit/swidth... > > > > although i'm not sure i agree entirely with its choice for raid10: > > So do I, especially as it makes no checks for the amount of copies (3 in my > case, not 2). > > > it probably doesn't matter. > > This was essentially my question. For an array -pf3 -c1024 I get swidth = 4 * > sunit = 4MiB. Is it about right and does it matter at all? how many drives? -dean - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: XFS sunit/swidth for raid10
dean gaudet wrote: On Thu, 22 Mar 2007, Peter Rabbitson wrote: Hi, How does one determine the XFS sunit and swidth sizes for a software raid10 with 3 copies? mkfs.xfs uses the GET_ARRAY_INFO ioctl to get the data it needs from software raid and select an appropriate sunit/swidth... although i'm not sure i agree entirely with its choice for raid10: So do I, especially as it makes no checks for the amount of copies (3 in my case, not 2). it probably doesn't matter. This was essentially my question. For an array -pf3 -c1024 I get swidth = 4 * sunit = 4MiB. Is it about right and does it matter at all? - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: XFS sunit/swidth for raid10
On Thu, 22 Mar 2007, Peter Rabbitson wrote: > Hi, > How does one determine the XFS sunit and swidth sizes for a software raid10 > with 3 copies? mkfs.xfs uses the GET_ARRAY_INFO ioctl to get the data it needs from software raid and select an appropriate sunit/swidth... although i'm not sure i agree entirely with its choice for raid10: *sunit = md.chunk_size >> 9; *swidth = *sunit * md.raid_disks; i'd think it would depend on the layout of the raid10 (near, far, offset)... for near2 on 4 disks i'd expect swidth to be only 2*sunit... but for far2 on 4 disks i'd expect 4*sunit... but i'm not sure. it probably doesn't matter. -dean - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
XFS sunit/swidth for raid10
Hi, How does one determine the XFS sunit and swidth sizes for a software raid10 with 3 copies? Thanks Peter - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
