413 reputation
619
bio website collectserver.info
location Maidenhead, United Kingdom
age 39
visits member for 3 years, 2 months
seen Aug 18 at 10:26

I'm an Oracle certified Database Administrator

I've worked extensively with both Oracle and Postgres, in various roles from DBA to developer. I have a basic working experience with SQL Server and MySQL.


Jul
5
comment Website high availability without load-balancer?
... whereas my proposed setup would mean there is a negative impact for the duration of the downtime. This isn't acceptable and is exactly what I wanted to find out in advance by asking here, so thank you very much. Please tell me if if missed the point in though!
Jul
5
comment Website high availability without load-balancer?
I've read and re-read this and all the comments, and I think I now understand you. You know that my plan never involves changing the NS records, but you are cautioning that this will mean a "randomly slow experience" for (half of?) client DNS resolution during the downtime of one VM. Your mention NS updates is presumably referring to the theoretical case when we manually update NS records during extended downtime to mitigate this? During downtime the current setup doesn't affect new connections after the VM is detected as down, ...
Jul
4
comment Website high availability without load-balancer?
OK, thanks, you've been a great help!
Jul
4
comment Website high availability without load-balancer?
The new scheme breaks because of caching of where the name server is, and the old scheme breaks because of caching of where the web server is. Are these failure modes identical or (for example) are ISPs more likely to ignore TTLs on nameserver records?
Jul
4
comment Website high availability without load-balancer?
@MadHatter I've tried to clarify the question: we are happy with the less-than-perfect nature of DNS load-balancing - the current setup is adequate for the service. But I don't want to make it worse and I'm asking if the change I'm suggesting would do that.
Jul
4
comment Website high availability without load-balancer?
Thanks, I will look into haproxy. Just to note though, we are using DNS load balancing presently and it is fine for our needs - the question is really just about whether I'd be making things worse (in terms of HA, not load-balancing) with the change I'm suggesting
Jul
4
comment Website high availability without load-balancer?
oh wait, sorry @MadHatter, no there can't be a single point of failure
Jul
4
comment Website high availability without load-balancer?
@MadHatter that's not the current set-up (which distributes the load) but it is what I mean by "If load-balancing was not a requirement", yes
Jul
4
comment Website high availability without load-balancer?
@MadHatter is there an obvious alternative that doesn't involve IP sharing between locations (which is out of our budget range)?
Jul
4
comment Website high availability without load-balancer?
@Nathan DNS caching is an issue with the current setup, are you saying it would be worse?
Mar
22
comment RAID 0 InnoDB speed - Comparing 8 x 7,200 RPM drives or 4 x 15,000 RPM drives
8x7200 will have roughly the same average rotational latancy as 4x15k. However rotational latency isn't the only variable in seek time, plus there's a whole bunch of other factors affecting overall performance.
Jan
23
comment Set up RDS on multiple servers using PowerShell
Just what I was looking for, thanks. I'd seen that guide but not read through it properly (maybe because of the small writing!).
Jan
11
comment Splitting up RDS roles
I've edited in my rationale, thanks for the questions.
Sep
26
comment Slow software raid with SSDs
sorry, all three configurations: you'd need to show that both drives function the same on their own…
Sep
26
comment Slow software raid with SSDs
have you benchmarked the drives in both configurations? "web application is snappy at all times and the nightly jobs are about 10 times faster" sounds a bit subjective…
Jun
13
comment Best way to grow Linux software RAID 1 to RAID 10
+1, especially for step 3 ;)
May
7
comment Can I have a password that only works for Exchange (not the domain)?
That is very useful information about the restricted accounts, thanks. Do you know what version of Exchange is needed, eg 2010+ perhaps? If you have time to update your answer that'd be superb!
May
6
comment Can I have a password that only works for Exchange (not the domain)?
BES Express has worked out just fine. You mentioned ActiveSync, did you mean you can set up a (non BB or perhaps a BB10) phone with ActiveSync using a password that is not the users domain password?
May
6
comment Kernel panic during rsync
@JennyD, I switched to btrfs and had the same issue. Then I switched to LVM snapshots and the crashes have gone away. Still no idea why unfortunately.
Apr
10
comment Exchange wildcard certificate with openssl generated CSR
excellent, thanks!