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SSD Caching
Hi all,
I have a Hetzner EX-40 server with Debian Wheezy & a Hardware Raid controller. I am running 30+ call of duty game servers for my gaming community on it.In start the disk I/O was fine but now when I increased the number of servers to 30+ it has become terrible & servers lag.So I am planing to order a 240 GB SSD for caching & to get better disk I/O.Please tell me:
1.If this is possible with the setup I have?
2.Do I need any extra hardware other than the 240 GB SSD which I am planing to order?
3.If this is possible with this server can someone please post link of some guide or any link which is helpful because I am pretty new to this SSD caching thing.I know several people especially the providers do this so I thought this might be the good place to ask for help
Thank you in advance for all your help!
Comments
SSD-Caching is a great way to speed up your disk access. You don't need any extra hardware, however some LSI RAID cards have the ability to do the SSD caching for you. What RAID card have you got?
As for SSD-Caching, I would recommend EnhanceIO. It is based on facebook's Flascache but has a lot of improvements. There is a guide here:
http://www.thislinux.org/2013/05/enhanceio-how-to-setup.html
*the guide is in Russian, but you can get the gist of it
You will need linux Kernel 3.9 or higher
Thank you for the link although it is in Russian
the HW controller is adaptec not LSI, so I can still do SSD caching using enhanceio even if I don't have LSI raid card?
Yeah, enhanceio just uses any disk for the caching within Linux.
Have you used it in any production systems? I looked at fastcache and a few other options previously and none of them really seemed ready for productions systems
@prae5 We are using EnhanceIO at the moment and have noticed good performance. We previously used flashcache for a year and had 100% uptime on our storage server with it. I can safely say flashcache and EnhanceIO are definately ready for production use.
Hmmm, might be time to look at them again, thanks
We are always evaluating their performance. Technically the longer they are online, the better the performance should be. Currently our cache has a read hit percentage of 72% and write of 6%.
Also, the advantage of EnhanceIO is that you can bring the Cache online and offline while the systems are live without affecting anything
Sounds like its definitely worth a look - something to do this weekend
@prae5 Let me know what you find out.
When I tried flashcache a while ago with KVM virtualization, linux guests work perfectly fine but I always get corrupted Windows guests after some time. Could be just me though.
We never got this. What exactly happened to the Windows guests? We run on Xen though, so could be a KVM issue.
In most cases the guest still runs fine, and in some cases random services failed to operate. The most weird thing is that the login box will definitely go missing, be it connected from RDP or console session, and guest reboot would always land at the recovery console. The symptom simply looks like someone messed up the Group Policy, and doing recovery will not go anywhere.
Well yeah it's KVM host with local storage, and my guess is that this doesn't affect SAN storage. Besides, linux guests on the same node work just fine without any issue.
Again it could be just me.
It is encouraged by kernel maintainers, for adoption. But in reality most distros (including wheezy) don't have such a recent kernel as stable. Newcomers shouldn't use EnchanceIO due to lack of documentation (and thus resulting in more unnecesarry obvious questions on forums and ESPECIALLY official mailinglists)
EnchanceIO is streamlined with the kernel, but has no raw performance difference from Flashcache.
I'd be curious about how much public development EnhanceIO will now receive that STEC is part of HGST/WD. Might be best to stick with Flashcache
Flashcache is probably the best option, I don't see anything wrong with it and it just works.