Why do systems 'go down' or are very slow?

jsmoke

jsmoke

jsmoke

Soldato
Joined
17 Jun 2012
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Many many times over the years a system will be slow or even down, you may phone up some company and 'their sorry as their system is slow today' . I've just been to the dentist to make an appointment and their system is down.

So what actually causes this, why would a system be slow especially if it's an internal system i.e an intranet.

Is it lack of ram, lack of CPU, or some setting/software?
 
From my experience, if it's down it is usually software bugs, failed updates or similar from my experience.

If it's slow, it's usually either poorly optimised or client machines being cheap
 
Avalon said:
How long is a bit of string?
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This! - could be a million things.

Extending on Hyburnate's list:
- Hardware failing
- Reliance on other infrastructure (power/cooling/connectivity)
- Real-world events (think of Ticketmaster on Glastonbury ticket selling day!)
- Security/Cyber attacks
 
But it happens too often, I phoned up both the DVLA and BT and the same thing, 'sorry our systems are really slow today', then 3 mins later.... It may have been a peak time and their network wasn't up to the task, in other words if you opened up the server it would be slow and croaking away. If that's the case then it makes sense, however surely they would have enough scalability for a large company as they are, an extra server here or there etc.

Updates could definately be the issue, I get that.

DDOS attacks even, but that's on the WAN side and shouldn't affect the LAN side I think.

Hardware failing again could be the issue.

Apart from that it's not entirely obvcious unless someone is downloading pr0n or the like but teven that would only affact the internet and shoudn't effect the LAN network.
 
jsmoke said:
But it happens too often, I phoned up both the DVLA and BT and the same thing, 'sorry our systems are really slow today', then 3 mins later.... It may have been a peak time and their network wasn't up to the task, in other words if you opened up the server it would be slow and croaking away. If that's the case then it makes sense, however surely they would have enough scalability for a large company as they are, an extra server here or there etc.

Updates could definately be the issue, I get that.

DDOS attacks even, but that's on the WAN side and shouldn't affect the LAN side I think.

Hardware failing again could be the issue.

Apart from that it's not entirely obvcious unless someone is downloading pr0n or the like but teven that would only affact the internet and shoudn't effect the LAN network.
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You're wrongly assuming that everything is network related though.

BT/DVLA are not likely to pay out for a HA cluster with several 9's of reliability/uptime just for their customer information systems. It would be a colossal waste of money.
 
Not sure why this is in the networking section. System performance issues are rarely the network. IME under provisioned systems that gain greater usage over time is a big one as is the introduction of software bugs in updates at the back or front end that cause things like memory leaks or inefficient calculations that only show up gradually. But there are a million and one reasons really.
 
BigT said:
Not sure why this is in the networking section. System performance issues are rarely the network. IME under provisioned systems that gain greater usage over time is a big one as is the introduction of software bugs in updates at the back or front end that cause things like memory leaks or inefficient calculations that only show up gradually. But there are a million and one reasons really.
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What Big T said is true, I work for a networking company, and usually it isn't the network that is problematic, although I'm not going to deny many companies still have 1G backbones which sometimes doesn't help.
 
Semple said:
You're wrongly assuming that everything is network related though.

BT/DVLA are not likely to pay out for a HA cluster with several 9's of reliability/uptime just for their customer information systems. It would be a colossal waste of money.
Click to expand...

DVLA have actually, I can get any drivers data in milliseconds via their API. (Only drivers who have authorised my software to do so of course ;))
 
I work at a council and we use Windows 8.
A week ago a Windows security update made all but our C drives disappear meaning we couldn't do any work for the rest of the day. No access to emails or the databases we use.
 
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