From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adam Goryachev Subject: Growing RAID5 SSD Array Date: Thu, 13 Mar 2014 13:49:01 +1100 Message-ID: <53211C9D.8050607@websitemanagers.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Hi all, About a year ago I setup a RAID5 array with 5 x Intel 480GB SSD's, (with a huge amount of help from the list in general, and Stan in particular, thanks again). Now I need to grow my array to 6 drives to get a little extra storage capacity, and just want to confirm I'm not doing anything crazy/stupid, and take the opportunity to re-check what I've got. So, currently I have 5 x Intel 480GB SSD: Device Model: INTEL SSDSC2CW480A3 Serial Number: CVCV205201PK480DGN LU WWN Device Id: 5 001517 bb2833c5f Firmware Version: 400i User Capacity: 480,103,981,056 bytes [480 GB] Sector Size: 512 bytes logical/physical Device is: Not in smartctl database [for details use: -P showall] ATA Version is: 8 ATA Standard is: ACS-2 revision 3 Local Time is: Thu Mar 13 13:40:20 2014 EST SMART support is: Available - device has SMART capability. SMART support is: Enabled md1 : active raid5 sdc1[7] sde1[9] sdf1[5] sdd1[8] sda1[6] 1875391744 blocks super 1.2 level 5, 64k chunk, algorithm 2 [5/5] [UUUUU] /dev/md1: Version : 1.2 Creation Time : Wed Aug 22 00:47:03 2012 Raid Level : raid5 Array Size : 1875391744 (1788.51 GiB 1920.40 GB) Used Dev Size : 468847936 (447.13 GiB 480.10 GB) Raid Devices : 5 Total Devices : 5 Persistence : Superblock is persistent Update Time : Thu Mar 13 13:41:03 2014 State : active Active Devices : 5 Working Devices : 5 Failed Devices : 0 Spare Devices : 0 Layout : left-symmetric Chunk Size : 64K Name : san1:1 (local to host san1) UUID : 707957c0:b7195438:06da5bc4:485d301c Events : 1712560 Number Major Minor RaidDevice State 7 8 33 0 active sync /dev/sdc1 6 8 1 1 active sync /dev/sda1 8 8 49 2 active sync /dev/sdd1 5 8 81 3 active sync /dev/sdf1 9 8 65 4 active sync /dev/sde1 One thing I've noticed is that on average, some drives seem to have more activity that others (ie, watching the flashing lights), however, the below stats from the drives themselves: /dev/sda 241 Total_LBAs_Written 0x0032 100 100 000 Old_age Always - 845235 242 Total_LBAs_Read 0x0032 100 100 000 Old_age Always - 1725102 /dev/sdb 241 Total_LBAs_Written 0x0032 100 100 000 Old_age Always - 0 242 Total_LBAs_Read 0x0032 100 100 000 Old_age Always - 0 /dev/sdc 241 Total_LBAs_Written 0x0032 100 100 000 Old_age Always - 851335 242 Total_LBAs_Read 0x0032 100 100 000 Old_age Always - 1715159 /dev/sdd 241 Total_LBAs_Written 0x0032 100 100 000 Old_age Always - 804564 242 Total_LBAs_Read 0x0032 100 100 000 Old_age Always - 1670041 /dev/sde 241 Total_LBAs_Written 0x0032 100 100 000 Old_age Always - 719767 242 Total_LBAs_Read 0x0032 100 100 000 Old_age Always - 1577363 /dev/sdf 241 Total_LBAs_Written 0x0032 100 100 000 Old_age Always - 719982 242 Total_LBAs_Read 0x0032 100 100 000 Old_age Always - 1577900 sdb is the new drive obviously, not yet part of the array. So the drive with the highest writes 851335 and the drive with the lowest writes 719982 show a big difference. Perhaps I have a problem with the setup/config of my array, or similar? So, I could simply do the following: mdadm --manage /dev/md1 --add /dev/sdb1 mdadm --grow /dev/md1 --raid-devices=6 Probably also need to remove the bitmap and re-add the bitmap. Can anyone suggest if what I am seeing is "normal", and should I just go ahead and add the extra disk? Regards, Adam -- Adam Goryachev Website Managers www.websitemanagers.com.au