[DRBD-user] IOPS Penalty when using DRBD

David Whiteman davew at supanet.net.uk
Tue May 8 13:21:16 CEST 2012

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


Hi,

I am currently designing a replacement to our MailDir email storage. We 
have decided to go with 2 storage servers, replicated using DRBD. What I 
want to know is the IOPS penalty DRBD will introduce.

I have measured the IOPS currently hitting our current servers, and used 
a std dev of this to determine the IOPS I need the new servers to be 
able to handle. I have calculated the read and write percentage and 
multiplied the write percentage by 2 (as we are using RAID 10 on the new 
servers). I failed to take into account DRBD with these calculations and 
so need to redo them.

RAID 10 has a "penalty" of 2, so it was pretty easy to multiply the 
write percentage of IOPS by 2. Is there a similar equation for DRBD to 
work out how many extra IOPS my server has to process in order to meet 
the current workload of the current servers?

Thanks in Advance



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