Re: sacrifice H310 hardware r5 for lvm2 raid5+lvmcache

There may be a way to do it with omconfig / storcli / MegaCLI but
we just set the disk to "Non-RAID" in the boot up BIOS tool of the
RAID card (Ctrl-R).

Install the 'lsscsi' tool which is useful for seeing things in these cases
It will show something like

[0:2:0:0]    disk    DELL     PERC H310        2.12  /dev/sda

for a virtual disk but after converted to non-RAID (JBOD) it should show
something like

[0:2:0:0]    disk    ATA      ST2000DM001-1CH1 CC24  /dev/sda

depending on disk make/model.  /dev/sda will also suddenly be a few
cylinders bigger.

You want to wipe any partition table the OS finds on the disk as it will have 
number of cylinders.  So something like

    dd if=/dev/zero of=/dev/sdX count=1 bs=4k

should do it.  Then run parted / gdisk / whatever partition tool you like to 
recreate a new one.  Ignore any error about a backup GPT table

-- Paul Raines (http://help.nmr.mgh.harvard.edu)



On Mon, 27 Jul 2015 9:26am, lejeczek wrote:

> but would OMSA do it and without re-flashing the firmware? Or LSI's tool set 
> is needed?
>
> On 27/07/15 14:21, Paul Raines wrote:
>>
>>  I cannot comment on the issue of using the hardware RAID5 or not. However,
>>  I will say from experience that 1-disk virtual disks are bad idea.  If you
>>  are doing that, you should put the disks in JBOD mode instead. Doing a
>>  1-disk vdisk just puts an unnecessarily layer on top of disk I/O that
>>  gives a added failure mode for no purpose.
>>
>>  -- Paul Raines (http://help.nmr.mgh.harvard.edu)
>> 
>> 
>>
>>  On Mon, 27 Jul 2015 3:48am, lejeczek wrote:
>> 
>> >  what do you think?
>> > 
>> >  dump raid5? change each pdisk into vdisk exposing to OS and
>> >  instead run lvm raid5 on those vdisks with a cache device?
>> > 
>> >  thanks.
>> > 
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