disk: introduce data cache #1621
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Use a faster disk as a cache layer over cloud disk.
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mowangdk
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Basically this is a POC PR, Please transition the PR into a mergeable ones.
| return fmt.Errorf("must specify non-zero %s for dataCache", DataCacheSizeKey) | ||
| } | ||
| if d.Mode == "" { | ||
| d.Mode = DataCacheWritethrough |
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I prefer to enable Write-back mode by default to push the performance to its maximum potential. For data-critical applications like databases, the risk is mitigated at the application layer, where internal binlogs and WAL are already in place to ensure high availability and data consistency
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enable Write-back mode by default
Then we need to wait for write back on unstage. This could take quite a long time. So this should only be enabled at new Kubernetes version, which don't do force detach when the node is healthy.
For data-critical applications like databases
I'm not sure how much benifest there are. Database issues fsync() frequently, which will force write-back from Google search. And RAM can also hold some dirty cache. Do you think DBs need GBs of dirty cache that RAM cannot handle?
| }, | ||
| } | ||
| copy(conf.Info.File_name[:], path) | ||
| err = unix.IoctlLoopConfigure(loop, &conf) // Since Linux kernel 5.8 |
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TODO: add this limitation in docs
| omitfsck = true | ||
| } | ||
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| // Setup DataCache |
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We need to eliminate cache devices from the VFIO stack to prevent incompatibility issues.
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What type of PR is this?
/kind feature
What this PR does / why we need it:
Use a faster disk as a cache layer over cloud disk.
Which issue(s) this PR fixes:
Fixes #
Special notes for your reviewer:
Does this PR introduce a user-facing change?
Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.: