Microsoft Corp. took a big step back so Vista could take a big step forward. New storage features in the forthcoming Vista operating system reflect Microsoft's realization that its Windows operating system lagged competing platforms in storage management features. The new Vista sports an improved file system, native support for hybrid disk drives (H-HDD), volume shrinking, enhanced I/O prioritization and drive encryption features.
Storage I/O's lead analyst, Greg Schulz, sees these features as Microsoft finally owning up to the reality that storage management is no longer a peripheral to the Windows operating system but is needed as part of its core ecosystem. Schulz cites Vista's new transactional file system as evidence that Microsoft is finally getting serious about storage. "A journaling file system makes Vista more than just a platform to run games on," says Schulz.
File system improvements
Vista's Transactional NTFS, like Longhorn's transacted file system (TxF), allows users to preserve data integrity during unexpected error conditions. For example, if a computer fails while an application is saving information to disk, the data may be corrupted since the save operation is only partially completed. To prevent this from occurring, TxF opens the file in transacted mode, saves the file and then commits the transaction. If the system fails during the save operation, it restores the file to its pre-save condition which prevents file corruption.
The Vista file system also includes major revisions to support the SMB (Server Message Block) 2.0 protocol. One major pain point that SMB 2.0 addresses, is the chattiness of the SMB 1.0 protocol, according to Navjot Virk, a Microsoft Software Design Engineer. "SMB 2.0 supports an arbitrary, extensible way of compounding operations to reduce round trips making it less chatty than SMB 1.0", says Virk.
Vista manages file handles, as well. SMB 2.0 increases the number of concurrent open file handles that a server can support and the number of shares that a server can share out. SMB 2.0 also provides more durable file handles which prevents clients from loosing connectivity to servers if short network glitches occur.
Which protocol, SMB 1.0 or 2.0, is used is decided during the negotiation phase between the client and server when the client advertises to the server that it can understand the new SMB 2.0 protocol. "If the server understands the new SMB 2.0 protocol, it is selected, otherwise it falls back to SMB 1.0, preserving Vista's compatibility with down level machines though they loose the benefits of SMB 2.0," Virk says.
Hybrid drives speed I/O, save batteries
Another storage feature that Vista adds is its native support of H-HDDs, which will provide users short- and long-term benefits. Using flash cache and traditional platter space in their construction, Vista recognizes a hybrid drive by sending an ATA command to the H-HDD that lets Vista know whether or not it is an H-HDD.
Mobile users will see some immediate benefit using this feature. "An initial benefit that mobile users will realize is a performance boost as H-HDDs allow some random I/O to be serviced by flash rather than the spinning HDD platter, which can be up to 10 times faster for small pieces of data", say Matt Ayers, program manager on the Windows client team.
Microsoft also expects that H-HDDs will extend the lives of batteries and disk drive. Known as Windows ReadyDrive, H-HDDs cache disk reads and writes without needing to spin the disk drive. According to Hiroshi Sakakibara, product manager on the Windows client team, this saves battery power on the machine and can also prevent disk failures when using laptops while on the go. "Windows ReadyDrive makes your laptop more rugged since it is less likely the disk will be spinning and susceptible to damage as one is running from meeting to meeting", say Sakakibara.
A benefit that Storage I/O's Greg Schulz expects corporations to realize longer term is that application programmers will learn to capitalize on its performance capabilities by storing certain application data in the H-HDD's cache. Schulz observes, "AIX can already communicate with certain IBM lines of storage and tell them which data to keep in memory. I expect Windows applications to eventually take advantage of this feature as well."
Another new Windows Vista feature, Volume Shrink, is one that at least one user questions how much value it will provide. The shrink volume allows users to reduce the size of a disk volume so administrators may re-allocate the excess capacity for other purposes. David Stevens, a systems manager at Carnegie Mellon University in Pittsburgh and a Windows Vista beta tester, doubts he will have much use for it: "From a macro storage perspective, this feature makes SAN-attached storage more difficult to manage since it does not help me to identify which LUNs (logical unit numbers) to recover and I potentially loose track of which application is using which storage," Stevens says.
Vista's enhanced ability to prioritise I/O was one feature that did intrigue Storage I/O's Schulz. While Windows already supports I/O prioritisation, the current implementation potentially introduces head-of-line blocking. Schulz analogizes, "This problem is akin to two [cars] going side by side down the Interstate at 40 mph. They have top priority but they slow everyone else down behind them."
Vista corrects this current Windows implementation issue by allowing even threads with a low priority to be given a higher priority so it is added to the job queue and serviced by the Windows operating system on a regular basis. This allows administrators to set tasks like disk defragmenter to run in the background at a low priority. In this way they do not impact production applications but also know that Vista will not entirely ignore the task either.
Another I/O prioritisation feature is Windows Vista improved ability to recognize and manage streaming data. Media applications often can begin their task while still retrieving data from the disk and can compensate for missing or dropped packets. Vista accommodates these applications by allowing the application to reserve minimum and maximum amounts of bandwidth within Vista's I/O subsystem. This guarantees application has the minimum throughput needed to stream video without glitches but also permits it to pre-fetch additional data when more bandwidth is available without choking other applications running on the system.
Increased storage security
Finally, Vista steps up its support for security of both fixed and removable media with its new BitLocker Drive Encryption feature. This feature's primary objective is to encrypt data on the Windows operating system volume of the hard drive to protect unauthorized users from breaking Windows file and system protection on lost or stolen computers. The data is encrypted based upon either a user-supplied personal identification number (PIN) or an inserted USB flash drive that contains the keying material. All encryption keys are then protected using the Trusted Platform Module (TPM) 1.2, a standard that uses trusted hardware and enabling software for security that is less vulnerable to virtual and physical attack.
In the event the user forgets his PIN or if the USB flash drive is lost, Vista also provides an option for administrators to recover the lost keys. To do this, Russ Humphries, lead program manager for Microsoft, recommends that an administrator assist the user in the setup of the BitLocker functionality using an Active Directory Group Policy Object. Then when the user either enters the key or inserts the USB device, the recovery key can be automatically escrowed into AD.
Storage I/O's Schulz concludes that these new storage features included with Windows Vista means that Microsoft finally realized that it had to address storage so it could bring all other operating system resources into balance. Schulz summarizes, "With these new storage management features in Vista, it is evident that storage is no longer a peripheral issue when Microsoft designs its operating systems but much closer to its core."
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