Realcache: Ssd Read Cache; Read Cache - Seagate AssuredSAN 3xx4 Configuration Manual

Config Guide
A:
Q: Are there performance implications when deleting one or multiple snapshots?
A:
Q: Can a snapshot of a snapshot be taken?
A:
Q: Can the new copy services snapshots be used with standard linear VDisks?
A: No, virtual storage and storage pools are not compatible with traditional VDisks
Q: Can multiple volumes be snapshotted at the same time?
A: Yes, this functionally is similar the existing DMS functions.
Q: Are snapshots with the new copy services application consistent?
A:
8.7. RealSpan: Asynchronous Replication
RealStor users create storage pools by creating and adding Virtual Disk Groups into a Virtual Disk Pool. The new copy services
run within these pools and leverage the new storage page design. GL220 introduces Asynchronous Replication over IP for
virtual pools, enabling replication between all AssuredSAN models for business continuity, data protection and disaster
recovery.

8.8. RealCache: SSD Read Cache

8.8.1. SSD Read Cache
A read cache is a special-purpose disk group dedicated to hold volatile copies of data within one or more SSDs. An
SSD read cache is a new concept in RealStor.
Some advantages of a read cache are:
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The read cache becomes active when the controller cache is saturated. The controller cache software gives "hints" to
the system software about which pages it would like to keep, but can't. The system then copies these pages into the
read cache. Reads are served from the SSD, and writes are written to both SSD and HDD.
A read cache is created using the Add Disk Group dialog box. From the Storage Management Console:
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83-00006911-00-01 Rev B
No, as each volume (or snapshot) is treated as a standard volume with reference pointers back to the source
volume, snapshots have the same performance profile as the original source volume.
No, all information relating to snapshots is using reference pointers, once these pointers are deleted the virtual
storage services de-allocates the required pages from the overall system map.
Yes, due to the new design of copy services each snapshot is treated as a peer volume and has all the
functionality of the original volume.
Yes, new copy services support Microsoft VSS and VMware VAAI, consistency outside of these areas will
require scripting and sample scripts can be provided.
Improved performance in read-centric workloads where maximum IOPS is crucial
Requires fewer SSDs when compared to a dedicated SSD tier.
A single SSD disk can be used as a read cache for a storage pool; whereas, an SSD tier requires multiple disk
to provide fault tolerance.
Takes advantage of tiering-like algorithms so that only active pages are copied into the read cache.
Active pages can be from any volume within the pool.
Click on the "Pools" icon in the navigation menu to the left.
Click the "Action" menu, and select the "Add Disk Group" menu item.
AssuredSAN 3xx4
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