Dear all,
I'm sory I didn't get the time to read the whole list and my Internet
researchs kept sending me to linux soft-raid howtos. So I send a mail to
this list.
This is the second time I travelled in the past due to my linux soft
RAID 1 system (mis)configuration.
Here is what I can say :
- I've got plenty of production servers configured in RAID 1 using the
2.4.24 debian patched linux kernel.
- I often go on those machines and a cat /proc/mstat seems to report me
that disks are synchronized. Should I trust this kind of information ?
- Those machines often turn more than a year long without being reboot.
- Sometime due to hardware problems, or a need for a kernel change I
have to reboot them.
- Sometime this reboot fail.
- This morning, it failled and I needed to use a Knoppix CD to get back
to my system, chroot, repair the problem and reboot.
- I needed to assemble my array before to mount it, what I did with :
mdadm --assemble /dev/md0 /dev/sda1 /dev/sdb1.
- The system answered it had to resynchronize the disks.
- After this, the data I got were about one year ago...
My opinion and questions :
- I thought that in RAID 1, writes were made on the 2 disks and reads
half/half on the first and the second. Am I wrong ?
- I've got the feeling that starting a certain day (don't know which
one), it stopped behave this way. Is this happening often ? Is it a bug
? How to detect this behaviour ?
- When I re-assembled the disk : no luck, it resynchronized the older
with the knew one, so I get in the past.
Please help me, telling me if it's a misunderstanding on the way RAID 1
should work, if I had to make more control with special tools, if it's a
bug, if it depends on the kernel version...
EG
--
========================================================================
Édouard GAULUÉ
ENSG - IGN Réseau et Systèmes Informatiques
6-8 avenue Blaise Pascal Activité IGS & DORIS
F-77455 MARNE LA VALLEE CEDEX 2 Master MSIAG
Tel : +33 (0) 1 64 15 32 43
Mail : Edouard.Gaulue@xxxxxxxxxxx
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