Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hi all,
sorry again for disturbing, but I'm still quite confused from the difference
between flexible-meta-disk and meta-disk. My concern is I will never use
DRBD on top of device that is bigger than ~50G, so I would like to save
metadata space, if it is possible.
I was wondering I can simply change all my
meta-disk /dev/VolGroup00/drbd_meta[0...]
with
flexible-meta-disk /dev/VolGroup00/drbd_meta[0...].
But I cannot:
# drbdadm -d adjust all
/etc/drbd.conf:98: Parse error: ';' expected,
but got '[' (TK 91)
Tried to use it without index:
flexible-meta-disk /dev/VolGroup00/drbd_meta
# drbdadm -d adjust all
/etc/drbd.conf:131: conflicting use of meta-disk
'vsp9.du.rnd.avaya.com:/dev/VolGroup00/drbd_meta[flexible]'
...
/etc/drbd.conf:100: meta-disk
'vsp9.du.rnd.avaya.com:/dev/VolGroup00/drbd_meta[flexible]'
first used here.
The docs states:
"With the flexible-meta-disk keyword you specify a block device as meta-data
storage. You usually use this with LVM, which allows you to have many
variable sized block devices."
Does flexible-meta-disk means I have to have one block device per each MD
device? If yes, what is the point of the whole flexible-meta-disk
definition?
Docs: "You must not use *[index]* with internal."
OK, I'm not using internal at all:
Next, there is a note there:
"Note: Regardless of whether you use the meta-disk or the
flexible-meta-diskkeyword, it will always be of the size needed for
the remaining storage
size."
Does it mean that I do not need to care about using flexible-meta-disk, I
can use simple meta-disk and I will only use the space that is required (no
fixed 128MB)?
Thanks.
2009/3/13 Maros Timko <timkom at gmail.com>
> Thanks Lars,
>
> please see comments below.
> 2009/3/13 Lars Ellenberg <lars.ellenberg at linbit.com>
>
>> On Fri, Mar 13, 2009 at 11:01:05AM +0000, Maros Timko wrote:
>> > Hi all,
>> >
>> > I wonder why user documentation states how to estimate required DRBD
>> > metadata size for external metadata:
>> >
>> http://www.drbd.org/users-guide-emb/ch-internals.html#s-external-meta-data
>> > when it is quite hardcoded value. At least example drbd.conf file still
>> > includes this information (128MB for each DRBD resource).
>>
>> there is meta-disk, and there is flexible-meta-disk.
>>
>> man drbd.conf
>
>
> Wow,
> I thought flexible-meta-disk can be used for internal metadata only. I
> think I saw it somewhere in my first contact with DRBD. Fine, now I checked
> man drbd.conf and it in place since 8.2.6 so Mea Culpa. I should not simply
> lean on template drbd.conf
>
>>
>> > So did ahything chance with DRBD 8.3.0 regarding external metadata size
>> > requirements?
>>
>> with drbd 8.3, you can use up to 16 TiB storage (well, you should not
>> have that exact amount, rather some sectors less).
>>
>> that would need 512 MiB worth of bitmap, plus the usual few KiB
>> for "superblock" and activity log.
>>
>
> But then it is quite interesting. If I am using meta-disk I cannot attach
> device that is larger then 4TB and if I want to, I simply have to use
> flexible-meta-disk. I think I have a deja-vu from last December, there was a
> messages exchange regarding mounting of 16TB devices.
>
> What if I am using single LVM for multiple flexible-meta-disk devices
> (flexible-meta-disk /dev/sda6[0...]) and later on I decide to resize/extend
> the corresponding DRBD partitions - will this be handled by DRBD correctly
> without any user intervention? Or -- from performance point of view -- would
> it be prefarable to dump/import all the metadata blocks after such change?
>
>
>>
>> --
>> : Lars Ellenberg
>> : LINBIT | Your Way to High Availability
>> : DRBD/HA support and consulting http://www.linbit.com
>>
>> DRBD® and LINBIT® are registered trademarks of LINBIT, Austria.
>> __
>> please don't Cc me, but send to list -- I'm subscribed
>> _______________________________________________
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>>
>
>
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