Re: standard performance (write speed 20Mb/s)
flat view
From: Erwan Leroux <hidden>
Date: 2011-07-21 08:55:14
following is how i configured advanced format drives for raid 5 i created one partition on each disk fdisk -u /dev/sdX # -u change the unit displayed by fdisk to sector instead of cylinders, this way it's easier to configure # the table partition isn't really modifier until you send the w command, so if you messed up use the q to quit and restart #delete first partition of the disk, repeat until you had cleared the disk d # create a new partition n # select primary parition p #select number one (don't know if number is important, i guess it's means /dev/sdX1) 1 #select first sector, here is the catch, to properly align the disk, select 64 64 #select default for the last sector <enter> # Change type of partition #https://raid.wiki.kernel.org/index.php/Partition_Types #according to this link if you use the option --metadata 1.2 with madadm --create # it's better to use the type DA (Non-FS data) instead of FD (Linux raid auto) but i can't found why # you can stick to FD, it's what is i used t DA or FD # commit the change so double check the setup with the p command before do it w Repeat the setup for each advanced format drives and you should be good to show you the result, here is the result of fdisk -l WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk doesn't support GPT. Use GNU Parted. Disk /dev/sda: 2000.4 GB, 2000398934016 bytes 255 heads, 63 sectors/track, 243201 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Device Boot Start End Blocks Id System /dev/sda1 1 243202 1953514552 fd Linux raid autodetect WARNING: GPT (GUID Partition Table) detected on '/dev/sdb'! The util fdisk doesn't support GPT. Use GNU Parted. Disk /dev/sdb: 2000.4 GB, 2000398934016 bytes 256 heads, 63 sectors/track, 242251 cylinders Units = cylinders of 16128 * 512 = 8257536 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Device Boot Start End Blocks Id System /dev/sdb1 1 242252 1953514552 fd Linux raid autodetect Disk /dev/sdc: 2000.4 GB, 2000398934016 bytes 255 heads, 63 sectors/track, 243201 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x78e9148d Device Boot Start End Blocks Id System /dev/sdc1 1 243202 1953514552 fd Linux raid autodetect WARNING: GPT (GUID Partition Table) detected on '/dev/sdd'! The util fdisk doesn't support GPT. Use GNU Parted. Disk /dev/sdd: 2000.4 GB, 2000398934016 bytes 255 heads, 63 sectors/track, 243201 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Device Boot Start End Blocks Id System /dev/sdd1 1 243202 1953514552 fd Linux raid autodetect WARNING: GPT (GUID Partition Table) detected on '/dev/sde'! The util fdisk doesn't support GPT. Use GNU Parted. Disk /dev/sde: 2000.4 GB, 2000398934016 bytes 255 heads, 63 sectors/track, 243201 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Device Boot Start End Blocks Id System /dev/sde1 1 243202 1953514552 fd Linux raid autodetect WARNING: GPT (GUID Partition Table) detected on '/dev/sdf'! The util fdisk doesn't support GPT. Use GNU Parted. Disk /dev/sdf: 2000.4 GB, 2000398934016 bytes 255 heads, 63 sectors/track, 243201 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Device Boot Start End Blocks Id System /dev/sdf1 1 243202 1953514552 fd Linux raid autodetect Disk /dev/md0: 10002.0 GB, 10001978490880 bytes 2 heads, 4 sectors/track, -1853078016 cylinders Units = cylinders of 8 * 512 = 4096 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 2097152 bytes / 10485760 bytes Disk identifier: 0x00000000 Disk /dev/md0 doesn't contain a valid partition table 2011/7/20 Pol Hallen [off-list ref]
quoted
This mishmash combo of drives, including two WD Green Advanced Format drives, is likely the cause of the horrible write performance. You're assembling the array from partitions.first of all: sorry but my english is not good :-( In many howto I read: "create a partition of disk and change it to "fd" code: linux raid autodetect" Now I re-done whole raid (I already have a backup) I have to create a partition on sigle disk? or remove any partition and stop?quoted
The partitions on the WD20EARS drives are undoubtedly not 4KB sector aligned, causing excessive read-modify-write cycles. See: http://en.wikipedia.org/wiki/Advanced_Format Repartition the Green drives with proper alignment. If you still have issues we'll go from there. Note: Having 3 dissimilar drives in an array is never going to be an optimally performing solution.Now I re-create a new raid system with 6 disks (everyone 2Tb wd) How do about 4Kb sector align? thanks! Pol
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