[DRBD-user] disk/partition/resource layout

dhz_bf at walla.co.il dhz_bf at walla.co.il
Wed Apr 7 09:49:01 CEST 2004

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


We had the same problem on our system.  We used to have one partition that held all the data we need to share between the primary and standby servers.
The data could be roughly divided into server related data and NFS exported data.  The problem we encountered is an overflow of the NFS exported data
prevented the server from functioning because it lacked space for the local data.
Consequently, we are now moving to a 2-partition configuration.  Drbd0 is used for the local data and drbd1 for the NFS exported data.

Regarding your concern about sync time, we have upgraded the system to 0.6.11 which contains the sync-group directive in drbd.conf.  It allows you to
have an order in the syncing activity, to prevent intereference between syncing activities of the partitions.  It syncs drbd0 first and then drbd1.
The sync time is no different than with one partition, since the overall amount of data you need to synchronize is the same.  We are now putting the new configuration into production, so I hope to have results soon as to whether the new configuration proves itself in the field.  Testing showed that it works well.

Relating to your configuration, our disk is smaller.  We are also using ext3 file systems..

Doron Zifrony
BladeFusion
dhz_bf at walla.co.il

<hmalte at you.oih.rwth-aachen.de>
[DRBD-user] disk/partition/resource layout

I've got two servers (x-connected via gigabit-NICs) which
should provide high availabilty NFS-service for a number of
web/mail/something front end servers.

I am currently planning on how to layout the existing
disk space:

a.) Multiple partitions "connected" via multiple
drbd-resources (drbd0, drbd1, ...). NFS-Exports:
/mnt/drbd0/ (mail), /mnt/drbd1/ (www), ...

b.) One big partition on one resource (drbd0). NFS-
Exports: /mnt/drbd0/mail/, /mnt/drbd0/www/, ...

Possible (Dis-)Advantages:

a.)
Pro: Potential file system corruption only affects one
partition and corresponding front end servers.
Con: Not recommended in DRBD documentation. First tests
show poor sync(-all) performance (as exptected).

b.)
Pro: Easy "DRBD-doc-recommended" setup.
Con: Potential file system corruptions cause failures
on all frontend servers.


Total disk size on each server is ~200GB. Expected number
of files: >800.000 with moderate I/O. Preferred file system
is ext3.

Any suggestions are welcome.

H.




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