That is quite scary Lets say I have 3x nodes each with 4x disks, a total of 12x disks. Two disk fails would mean a data loss if its set to 1 replicas, with 2 replicas it would mean no data loss but with the cluster availability of n+1 nodes it would take down the whole cluster if one disk failsin two hosts.
Maybe It would be smart to split the elasticsearch processes or run two VM's per host. https://codeascraft.com/2014/12/04/juggling-multiple-elasticsearch-instances-on-a-single-host/ If I did it like this then each process would have access to 2x disks meaning if one disk fails only two disks will be unavailable to the cluster instead of four. On Monday, December 15, 2014 12:05:18 PM UTC, Mark Walkom wrote: > > Unfortunately you lose all data on the node as ES will stripe segments > across the disks/mount points. > > On 15 December 2014 at 11:45, Elvar Böðvarsson <[email protected] > <javascript:>> wrote: >> >> If you have a node that has 4x disks as JBOD and you configure >> Elasticsearch to use all of them, so it will write to as like its Raid0. >> >> How does Elasticsearch handle a failure of one disk? >> Will the whole node go down or will Elasticsearch continue to function >> just with lower total available storage? (and then recreate the shards that >> went down) >> >> >> >> On Saturday, December 13, 2014 3:48:55 PM UTC, Jörg Prante wrote: >>> >>> The statement is related to performance and I can't agree with it. You >>> can easily build a RAID 0 system which has massive I/O throughput >>> performance and is superior to JBOD, because RAID striping does not slow >>> things down, it is as always as much as fast than a single drive and in >>> most RAID levels it is much faster. >>> >>> In the past, RAID was invented for mirroring cheap and error-prone >>> spindle disk arrays, while mirrors increase costs but decrease fault >>> probability. >>> >>> With Elasticsearch, the decision is if you still want to handle disk >>> faults by drive redundancy (RAID) and all other hardware faults like power >>> outages by server downtime. This is just a matter of organization and of >>> cost. I would suggest from my experience: take control over your complete >>> hardware setup, equip your systems with expensive SAS2 (or even better) >>> controllers with RAID 0 to reduce cost and maximize performance, and handle >>> all kind of hardware faults by server downtime, because ES replica level > >>> 0 allows that. >>> >>> There is also a simplification of SAN/NAS in the statement but that is a >>> different discussion. Never use SAN/NAS for ES local gateway. >>> >>> Jörg >>> >>> On Fri, Dec 12, 2014 at 7:28 PM, Elvar Böðvarsson <[email protected]> >>> wrote: >>>> >>>> >>>> Second, "Prefer JBODs for data disks over RAID, SAN/NAS", would be ok, >>>> maybe then to be safe go with 2x replicas, goes well with having 3x nodes >>>> >>>> -- >> You received this message because you are subscribed to the Google Groups >> "elasticsearch" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/elasticsearch/fad86579-2072-438d-94da-80219e200b67%40googlegroups.com >> >> <https://groups.google.com/d/msgid/elasticsearch/fad86579-2072-438d-94da-80219e200b67%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> >> For more options, visit https://groups.google.com/d/optout. >> > -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/elasticsearch/7e2260da-7082-4957-8302-57bf2a912b7b%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
