SSDs are not reliable after a (relatively-low compared to spinning disk) number of writes. They may significantly boost performance if used on the "journal" storage, but will suffer short lifetimes for highly-random write patterns.
In general, plan to replace them frequently. Whether they are worth it, given the performance improvement over the cost of replacement x hardware x logistics is generally a calculus problem. It's difficult to make a generic rationale for or against them. You might be better off in general by throwing more memory at your servers, and isolating your random access from your journaled data. Is there any pattern to your reads and writes/deletes? If it is fully random across your keys, then you have the worst-case scenario. Sometimes you can impose access patterns or structural patterns in your app which make caching more effective. Good questions to ask about your data access: Is there a "user session" which shows an access pattern to proximal data? Are there sets of access which always happen close together? Are there keys or maps which add extra indirection? I'm not familiar with your situation. I was just providing some general ideas.. Jonathan Shook On Wed, Nov 3, 2010 at 2:32 PM, Alaa Zubaidi <alaa.zuba...@pdf.com> wrote: > Hi, > we have a continuous high throughput writes, read and delete, and we are > trying to find the best hardware. > Is using SSD for Cassandra improves performance? Did any one compare SSD vs. > HDD? and any recommendations on SSDs? > > Thanks, > Alaa > >
