F-16 mdadm create 4 3tb RAID 5 array
| (Before I begin, let me apologize for the use of the open parenthesis. Turns out the forum software thought I was embedding URLS in my post! Pretty silly on a Linux site.) All, I've been struggling for quite a while with this but I'm very close to solving this problem. I am using a Zotac H67-ITX mobo with Fedora 16. I have upgraded the Intel OROM RST to 10.8 so I have RAID support of drives larger than 3TB. Hardware isn't an issue. (if it is, let's first try to resolve all software issues first. So, RAID 5, 4 drives, I'll have access to the disk capacity of all minus 1. So quick basic math: 3TB * 4 = 12TB - 3TB = 9TB. I'm expecting an array of 9tb when this is all done with. I started by blowing out the superblocks on all of these drives: [root}lox-itx ~]# dd if={dev{zero of={dev{sdb bs=1 count=2048 2048+0 records in 2048+0 records out 2048 bytes (2.0 kB) copied, 0.00702857 s, 291 kB{s [root}lox-itx ~]# dd if={dev{zero of={dev{sdc bs=1 count=2048 2048+0 records in 2048+0 records out 2048 bytes (2.0 kB) copied, 0.00266559 s, 768 kB{s [root}lox-itx ~]# dd if={dev{zero of={dev{sdd bs=1 count=2048 2048+0 records in 2048+0 records out 2048 bytes (2.0 kB) copied, 0.00435692 s, 470 kB{s [root}lox-itx ~]# dd if={dev{zero of={dev{sde bs=1 count=2048 2048+0 records in 2048+0 records out 2048 bytes (2.0 kB) copied, 0.00261023 s, 785 kB{s [root}lox-itx ~]# Let's get this party started: [root}lox-itx ~]# mdadm --create {dev{md0 --verbose --chunk=128 --level=raid5 --raid-devices=4 {dev{sdb {dev{sdc {dev{sdd {dev{sde mdadm: layout defaults to left-symmetric mdadm: layout defaults to left-symmetric mdadm: layout defaults to left-symmetric mdadm: layout defaults to left-symmetric mdadm: layout defaults to left-symmetric mdadm: layout defaults to left-symmetric mdadm: size set to 2930265344K mdadm: Defaulting to version 1.2 metadata mdadm: array {dev{md0 started. [root}lox-itx ~]# cat {proc{mdstat Personalities : [raid6] [raid5] [raid4] md0 : active raid5 sde[4] sdd[2] sdc[1] sdb[0] 8790796032 blocks super 1.2 level 5, 128k chunk, algorithm 2 [4{3] [UUU_] [>....................] recovery = 0.1% (3305656{2930265344) finish=797.8min speed=61141K{sec unused devices: <none> Ok, the array was made and it is busy syncing (initializing) it. Bad news, it set it as a 3TB size... now that is not what I want or am expecting. I query the array status: [root}lox-itx ~]# mdadm --detail {dev{md0 {dev{md0: Version : 1.2 Creation Time : Tue Dec 6 14:07:03 2011 Raid Level : raid5 Array Size : 8790796032 (8383.56 GiB 9001.78 GB) Used Dev Size : 2930265344 (2794.52 GiB 3000.59 GB) Raid Devices : 4 Total Devices : 4 Persistence : Superblock is persistent Update Time : Tue Dec 6 14:07:04 2011 State : clean, degraded, recovering Active Devices : 3 Working Devices : 4 Failed Devices : 0 Spare Devices : 1 Layout : left-symmetric Chunk Size : 128K Rebuild Status : 0% complete Name : lox-itx.action-unltd.com:0 (local to host lox-itx.action-unltd.com) UUID : 9ca54dcd:c87c676b:26b4853a:fa907eb1 Events : 1 Number Major Minor RaidDevice State 0 8 16 0 active sync {dev{sdb 1 8 32 1 active sync {dev{sdc 2 8 48 2 active sync {dev{sdd 4 8 64 3 spare rebuilding {dev{sde ----------------- Now wait a minute... 2 things have me confused. Maybe you can help me understand this. Take a close look at the following lines. Array Size : 8790796032 (8383.56 GiB 9001.78 GB) Used Dev Size : 2930265344 (2794.52 GiB 3000.59 GB) It states the array size it 9tb (what I want) and what does Used Dev Size mean? Also you see the last line? It claims that disk4 is acting as a spare!? I always thought a spare, or hot spare, was there, laying dormant, waiting to be brought alive when an array member disk failed and the array would be rebuilt on it, while the bad{failed disk was replaced (to take the place of the new spare) I actually don't want a (hot)spare. You guy know how much a 3TB hard disk costs these days? (Thai Flood) Well, then I say to myself, let's check the usable space: [root}lox-itx ~]# parted {dev{md0 GNU Parted 3.0 Using {dev{md0 Welcome to GNU Parted! Type 'help' to view a list of commands. (parted) p Error: {dev{md0: recognized disk label Model: Linux Software RAID Array (md) Disk {dev{md0: 9002GB Sector size (logical{physical): 512B{4096B Partition Table: unknown (parted) Holy cow, I got my 9TB! I guess I should be happy and I'm not at my wits end... (Told you I was close) Any of you guys familiar with mdadm (& large disks) and why it is reporting confusing info to me? Thanks, Lox |
No comments:
Post a Comment