[DRBD-user] Fwd: Re: Secondary Performance

Felix Frank ff at mpexnet.de
Thu Dec 20 13:43:39 CET 2012

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

Thanks, James, you seem to keep forgetting the list CC though ;)

-------- Original Message --------
Subject: Re: [DRBD-user] Secondary Performance
Date: Thu, 20 Dec 2012 11:40:27 +0000
From: Prater, James K. <jprater at draper.com>
To: 'ff at mpexnet.de' <ff at mpexnet.de>

What Felix suggested (switching roles) should work.  Personally,  I
would not use SSDs for that type of deploy.  It is best placed to speed
up certain processes (swap, scratch pad database location used for
indexes or anythi

----- Original Message -----
From: Felix Frank [mailto:ff at mpexnet.de]
Sent: Thursday, December 20, 2012 03:56 AM
To: Adam Goryachev <mailinglists at websitemanagers.com.au>
Cc: drbd-user at lists.linbit.com <drbd-user at lists.linbit.com>
Subject: Re: [DRBD-user] Secondary Performance

On 12/20/2012 08:31 AM, Adam Goryachev wrote:
> The primary has 5 x 480G Intel SSD drives in a RAID5 configuration
> The secondary has 4 x 2TB WD RE4 drives in a RAID10 configuration

Huh. SSD RAID vs. rotaries? That's about as far apart as you can set
primary and secondary performance-wise. Have you considered switching
their roles?

If I understand this correctly, you're looking for a way to keep your
maximum performance and trade in the stability of your replication. Are
you sure the gain is wort the risk (and pain)? Is your iSCSI maxing out
the I/O on that SSD RAID?

> In general, most of those are small amounts of data over small amounts
> of time, so it would be nice to add a little more buffering 'somewhere'
> so that instead of getting out of sync, the secondary just has more data
> un-written to disk in a buffer somewhere.
> Any suggestions or advice would be greatly appreciated.

DRBD Proxy springs to mind, even though that's not a free option
(monetarily speaking).


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