SCSI Solutions White Paper – HP-UX June 15, 2005 Executive Summary ......................................................................................................................... 2 1 SCSI Overview........................................................................................................................ 2 2 HP Solutions ........................................................................................................................... 5 3 Accessories ......................
Executive Summary This paper provides an overview of parallel SCSI (pSCSI) technology and solutions on HP-UX. A basic understanding of mass storage technologies is assumed. Topics discussed include: • pSCSI history and futures • HP pSCSI products and solutions • Configuration rules and guidelines • Online repairability and High Availability (HA) • Enclosure management • Performance and feature comparisons 1 SCSI Overview 1.
• Single-Ended (SE) – an electrical signal protocol that transmits information through changes in voltage. Single-ended SCSI uses standard TTL signal-to-ground pairs to transmit information over the SCSI bus. It is a low cost, low power solution, but the signal quality degrades rapidly which limits cable length to a maximum of 6 meters.
1.3 Futures The industry has agreed due to various problems inherent in parallel bus technology that there will be no progression of parallel SCSI beyond Ultra320. The parallel bus has inherent electrical issues with the timing of the various bits being transferred in parallel (skew), electromagnetic interference among the various parallel lines (crosstalk), and related issues which become increasingly difficult to address at higher speeds.
2 HP Solutions HP supports a range of pSCSI solutions for HP-UX servers, including disk storage enclosures, tape products, optical jukebox devices, and Host Bus Adapters (HBAs). Each of these is discussed below. 2.1 Disk Products The pSCSI disk products consist of disk drives and enclosures. The enclosures house multiple disk drives, and provide power supplies, fans, hot-swappable drive slots, and other management and availability features.
HP-UX 11i v2, HP-UX is delivering self-healing software in the Ultra320 HBA driver which will auto-detect signal integrity issues and downshift to Ultra160 speeds as needed. Other features of the DS2120 include: • 3.6TB of total storage per bus: up to three DS2120 enclosures can be daisy-chained in single-initiator configurations (providing a total of up to 3.6TB of storage on a single SCSI bus), and up to two DS2120’s can be daisy-chained in multi-initiator configurations (providing up to 2.
2.1.2.1 MSA30 Configuration/Deployment If shared buses are not required, the choice between SB and DB will depend upon the customer’s storage needs and other requirements. For example, a customer with small data storage needs may decide to connect a single MSA30 DB to two hosts, giving each host access to up to 7 disks. Each host can operate independently and not impact the other.
2.1.3 Older supported products Older supported disk products which are no longer sold by HP include the DS2100, DS2110, DS2300, SC10, HVD10, HASS, and AutoRAID 12H. The DS2100 and DS2110 are 4-slot Ultra160 SCSI disk enclosures in a 1U form factor with hot-swappable disks. They support Ultra320 disks and HBAs provided that the HBA is configured to operate at Ultra160 speeds (see the footnote regarding this in Section 2.1.2).
2.2 Tape Products HP supports a wide range of SCSI tape solutions for HP-UX servers, including various types of tape drives, autoloaders, and libraries. Currently available tape drives, from lower to higher capacity and speed, include the following shown in Table 2. Table 2: Tape Drive Products 1 1 2 3 4 Capacity Speed Reliability Power Form SCSI (GB) (MB/s) (GB/hr) (MTBF) (watts) Factor Interface Tape Drive Products 24 2 7.2 37.5 DAT 24 6 Fast Narrow SE DAT 4mm 40 6 21.6 7.
availability. The Tape Array can be connected to up to four separate HBAs connected to four different servers, or multiple drives in the enclosure can be daisy chained together and connected to a single HBA. The Tape Array 5300 supports a variety of DAT and Ultrium tape drives, as well as a DVD+RW drive. With the DVD+RW, the Q1592A product described in section 2.1.4 above, customers can read and/or write to CD or DVD in addition to tape, offering additional flexibility. See http://www.hp.
− − − − A6829A – PCI 2-port Ultra160 SCSI card A6828A – PCI 1-port Ultra160 SCSI card A5838A – PCI 2-port Ultra2 SCSI, 2-port 100base-t combo card A5159B – PCI 2-port FWD SCSI card All of these except for the FWD HBA work with LVD and SE devices, including SE Asynchronous, Fast, and Ultra devices, and LVD Ultra160, and Ultra320 devices. Only the FWD HBA directly supports HVD devices5.
The A9890A RAID card is a PCI-X 2-port Ultra320 SCSI RAID Controller which provides Advanced Data Guarding (RAID ADG), leading performance, 256MB Double Data Rate (DDR) battery-backed write cache architecture, and a new RAID engine. The A9891A is very similar to the A9890A card, the difference being that the A9891A has two additional SCSI ports for a total of four. The A7143A is a PCI 4-port Ultra160 SCSI RAID Controller with similar RAID and cache features.
3 Accessories 3.1 SCSI Bus Termination A SCSI bus is composed of a daisy chain of SCSI devices connected via SCSI cables. SCSI buses need to be electrically terminated at each end of the SCSI bus chain, and only at the ends. This termination is needed for proper operation of the bus. See Table 1 for details on the termination types needed with each SCSI bus type.
3.2 SCSI LVD-to-HVD Converter HP has recently certified an LVD-to-HVD converter to allow customers to use HVD disks with the newer LVD HBAs. The HP Hardware Provider (HPHP) program has successfully certified Rancho Technology’s LVD-to-HVD converter products on 11i v2 servers. This product meets the HP Hardware compliance testing criteria and is now officially “Certified for HP-UX”. This will enable customers who wish to continue using their legacy HVD devices on 11i v2 servers9.
4 Configuration Setting up parallel SCSI solutions requires careful attention to configuration issues and details. The following basic rules and definitions apply. Additional rules need to be considered in shared SCSI bus environments as discussed in Section 5. Basic Configuration Rules/Definitions Note: It is generally not recommended to mix disks with tapes or other non-disk devices on the same SCSI bus. This is due to performance and starvation issues that can result in mixed configurations. 1.
6. Bus Termination: Each end of a SCSI bus, and only the ends, must be terminated. If improperly terminated at the ends, bus integrity may be compromised. Termination in the middle can result in some devices being inaccessible. See the discussion on termination in Section 3 for additional details. 5 High Availability Configurations High Availability (HA) refers to the ability to keep a system or component operational (available) for a significant percentage of the time.
and disconnects the BCC from the enclosure’s internal bus, thus effectively isolating the BCC whose HBA has been disconnected from the rest of the bus and the other BCC. 6. DS2300 termination: Each BCC in the DS2300, whether in split-bus or full-bus mode, acts like a separate SCSI bus with respect to termination, and thus any unused port of a BCC whose other port is connected to an HBA must be physically terminated. See also section 3.1.2. 7.
6 Storage Management Storage management refers to the management and configuration of storage devices, enclosures, HBAs, and related components, including storage provisioning, backup planning, and the timely detection and recovery from hardware failures or exception conditions. Online management of storage hardware conditions, including drives, enclosures, and HBAs, is provided on HP-UX via the Diagnostics Event Monitoring Service (EMS) tools.
6.1.2 Tape Monitor The Tape Monitor (dm_stape) is designed to monitor the operation of individual tape drives, as well as various tape libraries and autoloaders. Predictive events monitored include “severe trouble reading or writing the tape”, which indicates that while no data has been lost, there has been a reduction in the performance or capacity of the tape, and it is recommended that the drive head be cleaned. 6.1.
6.2 Command View SDM HP StorageWorks Command View SDM (CVSDM) provides centralized storage management for DS2300 enclosures and various Fibre Channel disk array products. CVSDM allows for the centralized management of an unlimited number of the DS2300’s or other supported storage products from a graphical user interface (GUI), command line user interface (CLI), or Web browser. It provides secure device management in both direct-attach and SAN environments.
8 For more information http://www.hp.com/go/storage http://www.hp.com/go/unixserverconnectivity http://www.t10.org/ © 2005 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. The only warranties for HP products and services are set forth in the express warranty statements accompanying such products and services. Nothing herein should be construed as constituting an additional warranty.
