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Old 12-03-2007, 09:20 AM   #1
ufmale
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Registered: Feb 2007
Posts: 385

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RAID 5 with mdadm "spare" and "active sync" confusion


I am testing my RAID5 setup, and get confused on
"spare" and "active sync"

For md0, every drive has status "active sync", but md1 has one drive as "spare". I use the same mdadm cmd to build these 2 RAIDs, but not sure why it difference. My question is whether all 4 drives are used in the RAID array, or it indicates that one drive is failed. Any help would be great.

Code:
# mdadm --create /dev/md0 --level=raid5 --raid-devices=6 /dev/sdb[1-4] /dev/sde[1-2] 

# mdadm --create /dev/md1 --level=raid5 --raid-devices=4 /dev/sdc[1-2] /dev/sdc3 /dev/sdc5
Code:
# cat /proc/mdstat
Personalities : [raid0] [raid5]
md1 : active raid5 sdc5[4] sdc3[2] sdc2[1] sdc1[0]
      24121152 blocks level 5, 64k chunk, algorithm 2 [4/3] [UUU_]

md0 : active raid5 sdb2[1] sde2[5] sde1[4] sdb4[3] sdb3[2] sdb1[0]
      80364480 blocks level 5, 64k chunk, algorithm 2 [6/6] [UUUU

Here the output from

# mdadm --verbose --examine --scan

for md0 and md1 respectively

Code:
      

Number   Major   Minor   RaidDevice State
this     0       8       33        0      active sync   /dev/sdc1
   0     0       8       33        0      active sync   /dev/sdc1
   1     1       8       34        1      active sync   /dev/sdc2
   2     2       8       35        2      active sync   /dev/sdc3
   3     3       0        0        3      faulty removed
   4     4       8       37        4      spare   /dev/sdc5



      Number   Major   Minor   RaidDevice State
this     0       8       17        0      active sync   /dev/sdb1
   0     0       8       17        0      active sync   /dev/sdb1
   1     1       8       18        1      active sync   /dev/sdb2
   2     2       8       19        2      active sync   /dev/sdb3
   3     3       8       20        3      active sync   /dev/sdb4
   4     4       8       65        4      active sync   /dev/sde1
   5     5       8       66        5      active sync   /dev/sde2
 
Old 12-08-2007, 10:31 AM   #2
nass
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Registered: Apr 2006
Location: Athens, Greece
Distribution: slack(64|32)_v(13.37|14.0), debian6, ubuntu
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well mdadm is clever enough.
you only see one spare, which is SHARED between the 2 arrays (someone correct me if you think this is wrong)..
so it will not render 2/10 drives spare and waste your money

meanwhile you do seem to have a faulty drive there ..
 
  


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