Dot Hill Systems Corp. this week upgraded the RealStor storage management software with enhanced caching, capacity pooling and real-time tiering across solid state drives (SSDs) and hard-disk drives.
RealStor works with Dot Hill’s UltraSAN arrays, and is a particularly good fit for the Ultra48 AssuredSAN hybrid arrays that started shipping earlier this year. Dot Hill sells most of its storage systems through OEM partners, which include Hewlett-Packard (HP’s MSA systems come from Dot Hill).
Realstor 2.0 includes enhanced RealTier and RealCache features to manage data across SSDs and hard drives. RealTier, which previously only supported hard disks, now does autonomic data tiering across SSDs and hard disks.
“If I want better performances, then I have to pay for it, but we change it to give you better performance without the expensive costs,” said Jason Odorizzi, Dot Hill’s strategic product director.
Odorizzi said the RealTier scans and moves data within a five-second window so there is a negligible impact on the CPU while also boosting response times. Data is intelligently placed and moved across as many as three tiers, including flash, high speed disk, and near-line large capacity devices.
The RealCache read cache function also has been enhanced so that the RAID controller can see either 200 GB or 400 GB of extended cache. RealCache provides performance for peak workloads that exceed the controller’s memory cache capabilities. It also allows SSD cache to become an extension of the controller cache so IOP performances for read-centric workloads are increased. Also, one or more LUNs can be pinned to flash or any other storage tier.
“I can have peak workloads and have a much bigger cache and I can keep the entire workloads specific to reads,” Odorizzi said. “We can do tiering in parallel and if there are write workloads, we can read and write as well.”
RealStor’s RealSnap feature also has been updated with redirect-on-write snapshots that write only changes to new blocks, and can create snapshots any time. RealStor previously did copy-on-write snapshots that required the snapshots to be scheduled.
“As a result of redirect, I can get better RPO and RTO metrics,” Odorizzi said. “As I take more and more snapshots, the performance does not degrade. I can take a snapshot of a snapshot to make multiple copies and use it for different workloads and I don’t have to worry if it impacts the primary volume.”
The RealQuick capability has been enhanced to reduce the risk of data loss during a RAID rebuild because the software focuses first on restoring the bits of data and then the empty space on the storage media.
“The innovation is we want to minimize how long data is not available,” said Odorizzi.
The RealPool function has been upgraded to also virtualize SSDs instead of only pooling HDD capacity.
Brian Garrett, vice president of Enterprise Strategy Group’s lab, said the 2.0 version of RealStor has been improved to work in real-time.
“In my opinion, this is the next generation hybrid because a lot of hybrids don’t act in real time,” Garrett said. “This is more intelligent than policy-based software. It’s more real-time than scheduled.”