[linux-lvm] LVM on ATA-Raid Working - but Poorly

[linux-lvm] LVM on ATA-Raid Working - but Poorly

[Nathan Dornquast]

Hi all,

First, Thx to Heinz for not only writing great code, but taking the time to 
document and respond to inquires.

I have read the white paper and many, many mailings on this list, but I haven't 
seen anything addressing my problem.

Problem:
After creating LVM Vol Group (VG1) and single Log. Vol (lvol1) on ataraid 
mirrored drives (/dev/ataraid/d0p3) only one drives seems to get used.

I have repeated this process several times - 

1. Set up pvcreate - pvcreate /dev/ataraid/d0p1 - success

2. Run pvscan:  Reports
pvscan -- reading all physical volumes (this may take a while...)
pvscan -- inactive PV "/dev/ataraid/d0p3" is in no VG  [109.32 GB]
pvscan -- inactive PV "/dev/hdc3"         is in no VG  [109.32 GB]
pvscan -- inactive PV "/dev/hda3"         is in no VG  [109.32 GB]
pvscan -- total: 2 [327.96 GB] / in use: 0 [0] / in no VG: 2 [327.96 GB]

3. Run vgcreate -s 64 VG1 /dev/ataraid/d0p3 - success

4. Run pvscan: Reports
pvscan -- reading all physical volumes (this may take a while...)
pvscan -- ACTIVE PV "/dev/ataraid/d0p3" is in no VG  [109.32 GB]
pvscan -- inactive PV "/dev/hdc3"         is in no VG  [109.32 GB]
pvscan -- inactive PV "/dev/hda3"         is in no VG  [109.32 GB]
pvscan -- total: 3 [327.96 GB] / in use: 3 [327.96 GB] / in no VG: 0 [0] 

5. Create Logical Volume goes ok.. Format with ReiserFS - reports 109 GBs or so 
on mounting.  Life is good, right?  Until I reboot.

6. Reboot

7. Run pvscan: Reports
pvscan -- reading all physical volumes (this may take a while...)
pvscan -- inactive PV "/dev/ataraid/d0p3" is in no VG  [109.32 GB]
pvscan -- inactive PV "/dev/hdc3"         is in no VG  [109.32 GB]
pvscan -- ACTIVE PV "/dev/hda3"         is in no VG  [109.32 GB]
pvscan -- total: 3 [327.96 GB] / in use: 3 [327.96 GB] / in no VG: 0 [0] 

Hda3 becomes the active.. member?..    Drive activity seems to only occur on 
the first drive (which is what made me dig into this in the first place. I 
can't seem to make /dev/ataraid/d0p3 become active.  I've tried unsucessfully 
tor remove with pvchange -x y option for hda3 and hdc3, also tried vgremove.  
Doesn't seem to work.

If I make it a simple ReiserFS partition /dev/ataraid/d0p3 and mount it 
normally, both drives are active -- sharing writes and striping reads.

ATARaid support is in the kernel (no drives installed) and otherwise seems to 
work very well - booting off it and running well on several machines.

Some Specifics:
Debian 3.0, Kernel 2.4.19, Promise built in ata raid, LVM 1.0.4, 2x WD 120 GB 
drives.



..........
Nathan Dornquast
Aberon Technologies, Inc.
2205 California St NE - Suite 003
Minneapolis, MN 55418
w.612.789.9446
c.612.386.6519
..........

Re: [linux-lvm] LVM on ATA-Raid Working - but Poorly

[Goetz Bock]

On Wed, Oct 16 '02 at 23:50, Nathan Dornquast wrote:
> After creating LVM Vol Group (VG1) and single Log. Vol (lvol1) on ataraid 
> mirrored drives (/dev/ataraid/d0p3) only one drives seems to get used.
> [ ... ]
> 7. Run pvscan: Reports
> pvscan -- reading all physical volumes (this may take a while...)
> pvscan -- inactive PV "/dev/ataraid/d0p3" is in no VG  [109.32 GB]
> pvscan -- inactive PV "/dev/hdc3"         is in no VG  [109.32 GB]
> pvscan -- ACTIVE PV "/dev/hda3"         is in no VG  [109.32 GB]
> pvscan -- total: 3 [327.96 GB] / in use: 3 [327.96 GB] / in no VG: 0 [0] 
That's not an LVM problem, but still ...

You've two options:
- throw away the ataraid card, it is broken by design and get either a
  real RAID card (e.g. 3ware) or use the kernel based MD drivers
- if you want to keep the ataraid card, remove the regular ide drivers
  from your kernel. both drivers access the SAME hardware and make it
  available in two DIFFERENT locations. As the two drives /dev/hda and
  /dev/hdc and as the RAID1 drive /dev/ataraid/d0*
  as you have learned, the /dev/hd[ac] are much prefered and screw up
  your raid setup. OTOH you might be able to change the order the
  devices are tested in the LVM source code.

I'm running 4 boxes with MD based RAID1 discs (and 2 with RAID5) and 2
boxes with 3ware RAID1 (and one with RAID5) all with LVM and did never
have any trouble. 
If you want a cheap hardware RAID1-IDE solution the promise fasttrack
come with their own (I think closed source) driver that emulates a scsi
disk. As the IDE driver ignores the fasttrtack you can have a working,
bootable RAID1 setup with this cards. OTOH the 3ware is only 10-20$ more
expensive and comes with a cool monitoring tool. But if you get a
mainboard with a fasttrack controller it might be an interesting
solution. ... I would still get a 3ware ...
-- 
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