[DRBD-user] painfully slow sync

Dave Dunkin dave at gottathink.com
Tue Jan 27 05:35:25 CET 2004

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

On Jan 26, 2004, at 4:26 PM, Lars Ellenberg wrote:

> / 2004-01-26 15:48:14 -0600
> \ dave at gottathink.com:
>> Quoting Lars Ellenberg <Lars.Ellenberg at linbit.com>:
>>> / 2004-01-25 23:38:08 -0800
>>> \ Dave Dunkin:
>>>> I've got drbd set up on two RedHat 9 nodes with 60GB software RAID1
>>>> devices I'm trying to mirror. I started it up for the first time 
>>>> and it
>>>> started with a SyncAll from the primary to the secondary at around
>>>> 10MB/sec (on a private 100Mbps network). Then at almost exactly 30%
>>>> though the sync, the sync speed dropped to an abysmal 500KB/sec. 
>>>> I've
>>>> tried upping the minimum and setting the nice level, but nothing 
>>>> seems
>>>> to improve the situation. I tried stopping and restarting the sync
>>>> process and the same thing happened at 30%.
>>> you are sure that your /dev/md is not rebuilding at the same time?
>> /dev/md is not rebuilding.
> ? .... ?
> input?
> please provide more information, otherwise all we can do is guess.
> type and size of the lower level devices of your md, syslog,
> whatever seems remotely relevant...

Sorry, I don't really know what to look for. Both of the nodes are 
identical dual P3 550MHz, 1GB RAM. Kernel 2.4.20-28.9smp, drbd 0.6.10. 
The md device I'm using is 62.4GB software RAID1 of two identical IDE 
drives. The rest of the system partitions also live on these drives. I 
did just notice that I inadvertently put both drives on the same IDE 
channel. The system is nearly idle while it still syncs at <500KB/s 20 
hours later. Here's what vmstat has to say:

    procs                      memory      swap          io     system   
  r  b  w   swpd   free   buff  cache   si   so    bi    bo   in    cs 
us sy id
  0  0  0      0 706072  90144  91012    0    0   223    20  185   159  
0  2 98


Dave Dunkin
Software Architect
Gottathink, LLC

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