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questions about SSD cache, raid & solusvm
Hi everyone,
I want to provide some VPSes for free for my friends to play with. I'm not sure about a few questions. Could you guys please explain?
I'm gonna use a server with the spec: Dual L5520, 24G ram, 120SSD, 1x 1T enterprise level SATA, for the task.
I've never use SolusVM master / Slave. Due to the budget, I'm not using hard raid.
I wonder:
Is there any way to make the node 120G SSD-cached for that 1T SATA? (I know only the read will be improved a bit, not the write in this case). does centos support this? SolusVM allows this? how to get it work? or any better way to do it for 20 VPSes?
will this spec be able to handle 20 windows 2008 VPSes with 1G ram each? the CPU and I/O will be just enough? (if no one abuses)
Does SolusVM have the function that prevents users from occupying IP addresses that don't belong to them?
thanks
Comments
Flashcache. Yes, CentOS supports this. SolusVM doesn't have a problem with it. Here.
I don't see CPU being a problem. IO will bottleneck.
KVM has this functionality.
Thanks for your reply.
Regarding to the IO, 3 enterprise SATA in soft raid 5 should make the I/O alright for 20 VPSes?
what about just openvz for linux VPSes. still have this IP address function? no matter openvz kvm or xen?
If you were earlier looking at only 1x1TB SATA drive, why not go with 3 drives in soft RAID0? RAID5 without a good HW RAID card is going to suck. RAID0 would get you 300MB/s IO if each drive has 100MB/s. However, if you're going with Cloud Shards, their 24GB RAM servers don't support more than 2 3.5' drives. I haven't really played around with OpenVZ and Xen, so don't know about that. 3 drives in soft RAID5 should be just fine. Use this to calculate RAID speeds. I'd suggest you to use Xen PV if you want to run Linux, and KVM for Windows.
just realized your are from Gadgedz. I tried one of your 1G kvm product for a month. that was good~ thanks for answer.
since I "broke" 2 disks in one month from CVPS' dedi, I don't feel like using raid 0 anymore. Does 4 disks in raid 5 performs better than 3-disk raid 5 besides the utilization of the total capacity changed from 66% to 75%?
I tried 4 disks in raid 5 with VMWARE ESXI 5.1/5.5(that was in hard raid), it seemed faster than 3 disks in raid 5 or it's just my imagination? I don't know if it's gonna be faster in this case with soft raid 5.
Glad to know you had a good experience with us.
Cloud Shards is not like CVPS. However, it is always better to NOT use RAID0. Yes, 4 disks in RAID5 will perform better than 3 disks in RAID5. The more the drives, the better the performance. With 3x1T drives in RAID5, you get 2x read speed of 1 drive and 2T capacity. With 4x1T drives in RAID5, you get 3x read speed and 3T capacity. If you need an improvement in write speed as well, how about using RAID10? If you are only going to be using max 4 drives, soft RAID shouldn't be a problem. However, I've never used RAID5, so don't know more about it.
EDIT : You will see an improvement in performance using 4 drives as compared to 3 in soft RAID5 as well.
Read about RAID 5. It has read speed similar to RAID 0.
Good luck
thanks
It's not from Cloud Shards. thanks for all your answers. I will have a try.
Take a look at CacheCade 2.0 or Adapetc's maxCache 2.0 which work better than software based solutions. It doesn't need any kernel modules or something.