[GitHub] [pulsar] jiazhai commented on a change in pull request #8368: [Issue 8364][docs] Update decommission content in different releases

[GitBox <gi...@apache.org>]

jiazhai commented on a change in pull request #8368:
URL: https://github.com/apache/pulsar/pull/8368#discussion_r512024872



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File path: site2/website/versioned_docs/version-2.6.1/administration-zk-bk.md
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@@ -163,17 +163,50 @@ BookKeeper is responsible for all durable message storage in Pulsar. BookKeeper
 
 > For a guide to managing message persistence, retention, and expiry in Pulsar, see [this cookbook](cookbooks-retention-expiry.md).
 
-### Deploy BookKeeper
+### Hardware considerations
 
-BookKeeper provides [persistent message storage](concepts-architecture-overview.md#persistent-storage) for Pulsar.
+Bookie hosts are responsible for storing message data on disk. In order for bookies to provide optimal performance, ensuring that the bookies have a suitable hardware configuration is essential. You can choose two key dimensions to bookie hardware capacity:
 
-Each Pulsar broker needs to have its own cluster of bookies. The BookKeeper cluster shares a local ZooKeeper quorum with the Pulsar cluster.
+* Disk I/O capacity read/write
+* Storage capacity
 
-### Configure bookies
+Message entries written to bookies are always synced to disk before returning an acknowledgement to the Pulsar broker. To ensure low write latency, BookKeeper is designed to use multiple devices:
+
+* A **journal** to ensure durability. For sequential writes, having fast [fsync](https://linux.die.net/man/2/fsync) operations on bookie hosts is critical. Typically, small and fast [solid-state drives](https://en.wikipedia.org/wiki/Solid-state_drive) (SSDs) should suffice, or [hard disk drives](https://en.wikipedia.org/wiki/Hard_disk_drive) (HDDs) with a [RAID](https://en.wikipedia.org/wiki/RAID)s controller and a battery-backed write cache. Both solutions can reach fsync latency of ~0.4 ms.

Review comment:
       @codelipenghui . this is not only hdd, it is hdd with raid card(which contains cache)




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