Re: SSD as Cache?
On 11/08/2013 06:12 AM, basti wrote:
on my Webservers,
"Webservers" is plurar. Is there a database server? A file server?
How many servers do you have? Real or virtual? What is the topology?
Is this on the public Internet?
I have 1x 128GB SSD and a Raid 1 (1TB).
Now I plan to improve the performance of my Webapplication.
The Cache is about 10.0 GB in 2000000 files.
I'll assume the OS and application are on the SSD, and the application
data and cache are on the RAID.
How is the SSD partitioned? Make/ model/ version? Interface/
motherboard make/ model/ version? Any free space?
Tell us about the RAID. Hardware or software? Makes/ models/ versions
of drives/ interfaces/ software? File system? Any free interfaces,
drives, and/or space?
2E+06 files totaling 10 GB is a lot of small files. You will want a
dedicated partition with a file system created/ tuned for this purpose.
If your cache is not on such already (e.g. two 1 TB desktop HDD with
LVM RAID 1 and default ext4 files system), this may be your bottleneck.
Can this cache moved to SSD?
I would think so, if the application allows it and there is room on the SSD.
Months ago I read articles about SSD and Flash Memory like:
- "Disable logging on SSD"
- "Disable cache on SSD"
- "Don't swap on SSD" ...
And today?
How long will the SSD work without data loss?
The questions of 1) whether or not it will help and 2) whether or not
it's going to wear out your SSD are difficult to answer a priori without
intimate knowledge of your hardware, software, and usage patterns. The
simple answer is "go for it" for a week and see what happens.
It would help if you provided:
- hardware make/ model information.
- OS and software name/ version information
- system monitoring data -- CPU, RAM, cache, swap, drive, network, etc.,
usage, bandwidth, etc., for a typical usage period (1 week?).
- other constraints -- network bandwidth, network aggregate data limits
application source code and license, etc..
David
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