When I read documentation about Hbase it says RAID is not recommended for many cases. When we talk about SolrCloud (and consider that if a machine goes down there is a failure system via replicas) and when we think about the purposes of different RAID disks:
do they true -> using RAID systems for: * *fault tolerance*: does not make sense because there is already a mechanism at SolrCloud and instead of using my disks for such kind of RAID purpose I can use that disk at somewhere else for a replica? * *read and write performance:* I should select a RAID version for considering about a good performance of read/write. All in all maybe I should consider about Non-RAID drive architectures as like JBOD? What do you guys think about not considering RAID versions which has good fault tolerance but considering read/write performance and maybe considering about Non-RAID drive architectures? 2013/4/20 Shawn Heisey <s...@elyograg.org> > On 4/20/2013 7:36 AM, Toke Eskildsen wrote: > > Furkan KAMACI [furkankam...@gmail.com]: > >> Is there any documentation that explains pros and cons of using RAID or > >> different RAIDS? > > > > There's plenty for RAID in general, but I do not know of any in-depth > Solr-specific guides. > > > > For index updates, you want high bulk read- and write-speed. That makes > the striped versions, such as RAID 5 & 6, poor choices for a heavily > updated index. > > > > For searching you want low latency and high throughput for small random > access reads. All the common RAIDs gives you higher throughput for those. > > The only RAID level I'm aware of that satisfies speed requirements for > both indexing and queries is RAID10, striping across mirror sets. The > speed goes up with each pair of disks you add. The only problem with > RAID10 is that you lose half of your raw disk space, just like with > RAID1. This is the raid level that I use for my Solr servers. I have > six 1TB SATA drives, giving me a usable volume of 3TB. I notice a > significant disk speed increase compared to a server with single or > mirrored disks. It is faster on both random and contiguous reads. > > RAID 5 and 6 (striping with parity) don't lose as much disk space; one > or two disks depending on which one you choose. Read speed is very good > with these levels, but unfortunately there is a penalty for writes due > to the parity stripes, and that penalty can be quite severe. If you > have a caching RAID controller, the write penalty is mitigated for > writes that fit in the cache (usually up to 1GB), but once you start > writing continuously, the penalty comes back. > > In the event of a disk failure, all RAID levels will have lower > performance during rebuild. RAID10 will have no performance impact > before you replace the disk, and will have a mild and short-lived > performance impact while the rebuild is happening. RAID5/6 has a major > performance impact as soon as a disk fails, and an even higher > performance impact during the rebuild, which can take a very long time. > Rebuilding a failed disk on a RAID6 volume that has 23 1TB disks is a > process that takes about 24 hours, and I can say that from personal > experience. > > Thanks, > Shawn > >
