From: CSBVAX::MRGATE!RELAY-INFO-VAX@CRVAX.SRI.COM@SMTP 27-AUG-1988 14:59 To: ARISIA::EVERHART Subj: REVIEW: Exsys "RACE" disks Received: From KL.SRI.COM by CRVAX.SRI.COM with TCP; Sat, 27 AUG 88 02:59:18 PDT Received: from ucbvax.Berkeley.EDU by KL.SRI.COM with TCP; Sat, 27 Aug 88 02:40:04 PDT Received: by ucbvax.Berkeley.EDU (5.59/1.31) id AA01500; Sat, 27 Aug 88 02:03:55 PDT Received: from USENET by ucbvax.Berkeley.EDU with netnews for info-vax@kl.sri.com (info-vax@kl.sri.com) (contact usenet@ucbvax.Berkeley.EDU if you have questions) Date: 26 Aug 88 09:01:31 GMT From: attcan!utgpu!water!watmath!julian!uwovax!brent@uunet.uu.net Subject: REVIEW: Exsys "RACE" disks Message-Id: <620@uwovax.uwo.ca> Sender: info-vax-request@kl.sri.com To: info-vax@kl.sri.com Exsys "Race" Array Disks - A Review =================================== Brent Sterner, UWO The time has come to post my promised review of the disk technology we selected for our VAX cluster. To review, our cluster has an 8600 and an 8550 with peripherals on an HSC-50. The HSC had one power supply, one CA (tape) channel, and two BA (disk) channels. Seven RA81 disks hung from the 2 BA channels (ie room for just one more). The problem: add 1.5 gig of disk economically. Adding RA disks was considered due to the reliability we have had with the existing spindles. But the costs included adding a second HSC power supply to support a third BA channel *before* starting to add the spindles. And maintenance of RA81 disks is very high in today's market. After pondering newer technology disks which would plug into the HSC, we decided to purchase 2 gigabytes of Exsys disks and two ESDI/SDI converters and remove one RA81 disk, netting 1.5 gigabytes of storage increase and filling the last SDI channel on the second BA. The result is six RA81 disks and two "RA70" disks. The "RACE" concept is interesting. Exsys couples up to four ESDI disks (ours are MAXTOR model 8760E, but other disks are available) through one SDI/ESDI protocol converter, so that the HSC sees one SDI disk spindle. In our case we elected to purchase a second protocol converter to allow the resulting 2 gigabytes to be split onto two channels. Installation was completed in two phases. First the Exsys unit was placed on top of our star coupler and half the spindles were installed onto the last SDI channel. Two weeks later, after verifying that the existing spindles were functional and having migrated user files from one RA81, that RA81 was removed (with its rails) and the 5.25 inch cabinet was mounted in the RA quad cabinet. The previously unused MAXTOR drives were connected to the vacated SDI channel, and everything was complete. Except the filler pannel which has yet to be delivered. Hard to believe that 2.1 gigabytes of storage take exactly half the space of one RA81 (456 mb). To date the disks have exhibited no sign of any errors. (Of course only time will tell that story. :-) The instructions which came with the disks suggest initializing the disk with a cluster size of 5. Other sizes were never tried, so the author does not know if this is a restriction. Before installation, I had a look inside the box. Besides the four disk spindles, there are two converter boards. In case of failure, there are a half dozen connectors to remove from the board, as well as the mounting screws. (I suspect I could swap in a new board or drive myself, simply by observing the original connections. May be that's the *real* reason I ordered two channel converters. :-) No field repair here; just swap in a new part. The unit has a built in formatter and disk exerciser, complete with diagnostics. All can be initiated with a bank of dip switches on the front panel, or through a terminal which can be plugged into that same panel. It is hoped that none of these features will be required, but fault isolation to the board or spindle level seems to be available and adequate. The unit comes preformatted, literally plug and play. ILEXER was used on the HSC only briefly (10 minutes) before each pair of spindles was initialized. Finally, a snapshot of one of the RA70 devices: Disk HSC001$DUA7:, device type RA70, is online, mounted, file-oriented device, shareable, available to cluster, error logging is enabled. Error count 0 Operations completed 269217 Owner process "" Owner UIC [1_4] Owner process ID 00000000 Dev Prot S:RWED,O:RWED,G:RWED,W:RWED Reference count 12 Default buffer size 512 Total blocks 2142360 Sectors per track 44 Total cylinders 3246 Tracks per cylinder 15 Host name "HSC001" Host type, available HS50, yes Volume label "DISK7" Relative volume number 0 Cluster size 5 Transaction count 24 Free blocks 1166485 Maximum files allowed 178530 Extend quantity 6 Mount count 2 Mount status System Cache name "_HSC001$DUA0:XQPCACHE" Extent cache size 64 Maximum blocks in extent cache 116648 File ID cache size 64 Blocks currently in extent cache 4420 Quota cache size 240 Maximum buffers in FCP cache 815 Volume status: subject to mount verification, file high-water marking, write- through caching enabled. Volume is also mounted on UWOVAX. And yes, based on performance to date, I would purchase this product again (and may if our disk usage continues to grow the way it has in the last year).