If they aren't spanned, you'll only lose data that's on the one disk.Use the information in the next two sections to help set up Storage Spaces to handle disk and JBOD enclosure failures with minimal impact on service and minimal risk of data loss. I imagined a dual-disk enclosure would typically be spanning across disks. It's short for "just a bunch of disks", meaning that it's just like plugging the drives into a plain non-RAID controller and using them as plain, independent disks. LawrenceC LawrenceC JBOD doesn't mean that the disks are combined into a single logical volume. Say the chance of one disk being OK is 0. Be aware that the combined disk's fail rate will be significantly higher. James James 5 5 gold badges 14 14 silver badges 26 26 bronze badges. If one disk in a JBOD group fails, are files on other disks inaccessible? Ask Question. The best answers are voted up and rise to the top. With data arrays including RAID and JBOD you should have backup but my guess is that if you're using JBOD it's because you have lots of data and little money so that recommendation won't mean anything to you till you loose your irreplaceable data. If one drive fails the others will still be readable. I'm a raid guy 0, 1, 5 and have never used jbod, but it appears that losing a drive wil be the equivalent of having a volume with lots and lots of unreadable sectors that are unrecoverable.Īny data stored entirely on a still-working drive would be recoverable. You should really consider backups if you plan on using JBOD. If you lose the MFT, you are pretty much out of luck. That depends on where the MFT or equivalent was stored.
If you want to be able to access the volume if a disk in it fails you need some type of redundancy and pay for it with disk space, either hardware RAID or a software equivalent. If I use a dual-disk enclosure that employs JBOD, would I be able to at least access and use a second disk in the event that the other fails or otherwise becomes inaccessible? In a spanned volume, if one disk goes down, data on the entire spanned volume, i.ĪLL your data, is at risk. Super User is a question and answer site for computer enthusiasts and power users. The procedure for doing this depends on whether the cluster uses vnodes or single-token architecture.Ĭassandra tarball installations.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. However, if the disk crash corrupted the Cassandra system table, you must remove the incomplete data from the other disks in the array. It's possible that you can simply replace the disk, restart Cassandra, and run nodetool repair. Release notes for the Apache Cassandra 3. Solutions for migrating from other databases.Ĭorrecting a problem in the gossip state. Cassandra uses Bloom filters to determine whether an SSTable has data for a particular row. The compaction process merges keys, combines columns, evicts tombstones, consolidates SSTables, and creates a new index in the merged SSTable.Įnabling write survey mode. Configuring memtable thresholds to improve write performance. Steps for recovering from a single disk failure in a disk array using JBOD just a bunch of disks. Steps for restoring a snapshot by recovering the cluster into another newly created cluster. When incremental backups are enabled, Cassandra hard-links each memtable flushed to an SSTable to a backups directory under the keyspace data directory. Steps for taking a global snapshot or per node. A brief description of how Cassandra backs up data. Cassandra backs up data by taking a snapshot of all on-disk data files SSTable files stored in the data directory. Topics for adding or removing nodes, datacenters, or clusters. Cassandra operation topics, such as node and datacenter operations, changing replication strategies, configuring compaction and compression, caching, and tuning Bloom filters. Various installation methods.Ĭonfiguration topics. Vital information about successfully deploying a Cassandra cluster. Important topics for understanding Cassandra. Documentation for developers and administrators on installing, configuring, and using the features and capabilities of Apache Cassandra scalable open source NoSQL database. Can't find what you're looking for? Try searching other guides.