Buying hardware for virtualization
Do you know what is optimum CPU, memory, network, storage and redundancy for creating best possible server for virtualization?
Do you know what is optimum CPU, memory, network, storage and redundancy for creating best possible server for virtualization?
Virtualization is very extremely popular these days. Because who wouldn’t want to change servers into many virtual machines and can be turn on and off when needed? The only problem is special hardware that is needed to gain as much advantage from virtualization as possible.
It doesn’t matter if you are trying to build a big virtualization farm or just a small infrastructure - there are some basic guidelines that can help you understanding what hardware you need.
CPU
While choosing CPU you need to stick to one basic rule - the more cores the better. You would be surprised that even at lower CPU speeds (1.7GHz per core) you can get a good performance. Of course if you will have budged to go for faster chips - buy them. But even a slower 1.7GHz AMD Opteron 4000-series with six core per CPU can be a good choice for a virtualization platform.
In the past, there was a common knowledge that "the faster CPU the better" but that was only true when it comes to single-threaded tasks. During normal use, most CPU's will often stay nearly idle for significant portion of their cycles. Sometimes having faster CPU may not help, since processor may need to wait to access data from RAM, disk or network. That is if you can choice to buy slower six-, eight-, twelve-core CPU that have lower speeds and a four- or six-core CPU that is faster, always go for the one with higher core count.
MEMORY
Memory is the most important hardware in server since it is the biggest limiting factor in how many virtual servers you can run simultaneously. Therefore if you can put 64GB of RAM or even more into a server with 12, 16 or 24 cores then do it. Even when price of memory gets higher along with density it is better to use 4GB or 8GB sticks then a pile of 2GB, you don't want to buy another server just to use that memory, then except new server, you will also need new licenses.
RACK SPACE
In real world, you always need to be able to service the loss of one single physical server - ideally more than one if your infrastructure is big enough. There are some things that you just can't predict - fire, flood, earthquake or any other catastrophe.
You also need to set up a safe routine maintenance. If you won't be able to power off one server for 10 min just to replace a failed memory stick, then you are in trouble and you are losing one of the biggest benefits of server virtualization - less scheduled downtime. When one of physical servers needs to be powered down, you should avoid need to power down virtual servers in order to handle that loss. That is why running N+1 is a minimum.
STORAGE
Nowadays every virtualization platform should be build using shared storage. While running without this, any virtual machine cannot be protected against a physical server failure. Also expanding such storage can't be very difficult unless using some kind of iSCSI Target Software (check iStorage Server for more information). That is why shared storage isn't an option, it is a rule.
While choosing storage for your server, make sure it is as robust as possible. No matter if you plan to use iSCSI, NFC or Fiber-Channel, check your disk I/O needs before you will start planning your network. Still, unless you don't except any have transactional disk workload, you don't need to go for SSD or even SAS-bases arrays.
As a matter of fact if you are just about to utilize 10G for each server, using faster drives may be pointless. With use of cheap disks, you don't need to stick with RAID5, you can use RAID6 or even RAID10 arrays. Of course it will take more physical space but the performance and reliability will outcome the space issue.
NETWORK
While building network, you need to keep in mind that it is cheaper to use multiple 1G copper links rather than 10G, but don't forget that 10G will give you a huge growth potential. Usually general servers won't utilize whole 10G both for normal service traffic or disk I/O but highly transactional applications will so try to find balance based on your needs.
At last remember that server virtualization change your infrastructure to use fewer physical units, therefore the better hardware you have, the higher chance that it will fail you. With all money saved on power and cooling you will be able to add additional storage arrays that may help with replication and still be in the budget.
Hope that all those tips will help you build a solid and stable virtualization platform and that you will be able to enjoy many benefits that come from it.
Source:
http://goo.gl/C3cwk
iStorage Server – Software iSCSI Target:
http://www.kernsafe.com/product/istorage-server.aspx
(Free version also available.)
It doesn’t matter if you are trying to build a big virtualization farm or just a small infrastructure - there are some basic guidelines that can help you understanding what hardware you need.
CPU
While choosing CPU you need to stick to one basic rule - the more cores the better. You would be surprised that even at lower CPU speeds (1.7GHz per core) you can get a good performance. Of course if you will have budged to go for faster chips - buy them. But even a slower 1.7GHz AMD Opteron 4000-series with six core per CPU can be a good choice for a virtualization platform.
In the past, there was a common knowledge that "the faster CPU the better" but that was only true when it comes to single-threaded tasks. During normal use, most CPU's will often stay nearly idle for significant portion of their cycles. Sometimes having faster CPU may not help, since processor may need to wait to access data from RAM, disk or network. That is if you can choice to buy slower six-, eight-, twelve-core CPU that have lower speeds and a four- or six-core CPU that is faster, always go for the one with higher core count.
MEMORY
Memory is the most important hardware in server since it is the biggest limiting factor in how many virtual servers you can run simultaneously. Therefore if you can put 64GB of RAM or even more into a server with 12, 16 or 24 cores then do it. Even when price of memory gets higher along with density it is better to use 4GB or 8GB sticks then a pile of 2GB, you don't want to buy another server just to use that memory, then except new server, you will also need new licenses.
RACK SPACE
In real world, you always need to be able to service the loss of one single physical server - ideally more than one if your infrastructure is big enough. There are some things that you just can't predict - fire, flood, earthquake or any other catastrophe.
You also need to set up a safe routine maintenance. If you won't be able to power off one server for 10 min just to replace a failed memory stick, then you are in trouble and you are losing one of the biggest benefits of server virtualization - less scheduled downtime. When one of physical servers needs to be powered down, you should avoid need to power down virtual servers in order to handle that loss. That is why running N+1 is a minimum.
STORAGE
Nowadays every virtualization platform should be build using shared storage. While running without this, any virtual machine cannot be protected against a physical server failure. Also expanding such storage can't be very difficult unless using some kind of iSCSI Target Software (check iStorage Server for more information). That is why shared storage isn't an option, it is a rule.
While choosing storage for your server, make sure it is as robust as possible. No matter if you plan to use iSCSI, NFC or Fiber-Channel, check your disk I/O needs before you will start planning your network. Still, unless you don't except any have transactional disk workload, you don't need to go for SSD or even SAS-bases arrays.
As a matter of fact if you are just about to utilize 10G for each server, using faster drives may be pointless. With use of cheap disks, you don't need to stick with RAID5, you can use RAID6 or even RAID10 arrays. Of course it will take more physical space but the performance and reliability will outcome the space issue.
NETWORK
While building network, you need to keep in mind that it is cheaper to use multiple 1G copper links rather than 10G, but don't forget that 10G will give you a huge growth potential. Usually general servers won't utilize whole 10G both for normal service traffic or disk I/O but highly transactional applications will so try to find balance based on your needs.
At last remember that server virtualization change your infrastructure to use fewer physical units, therefore the better hardware you have, the higher chance that it will fail you. With all money saved on power and cooling you will be able to add additional storage arrays that may help with replication and still be in the budget.
Hope that all those tips will help you build a solid and stable virtualization platform and that you will be able to enjoy many benefits that come from it.
Source:
http://goo.gl/C3cwk
iStorage Server – Software iSCSI Target:
http://www.kernsafe.com/product/istorage-server.aspx
(Free version also available.)
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