| Title: | Ask the Storage Architecture Group |
| Notice: | Check out our web page at http://www-starch.shr.dec.com |
| Moderator: | SSAG::TERZA N |
| Created: | Wed Oct 15 1986 |
| Last Modified: | Fri Jun 06 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 6756 |
| Total number of notes: | 25276 |
Dear Team-mate,
One of our major customer in Hong Kong they are using DIGITAL
solid-state disk EZ54R has performance problem, which of course the
customer pointed out that the EZ54 cannot have 800 I/O's per sce as
stated in the SOC.
I have already explained to them for the low transfer control
circuitry of EZ54 of only 2.5 MB/sec. However, the customer want us to
give them the guideline on how to achieve 800 I/O /sec as the SOC, what
is the specification to get this wonderful result. I only need to know
the specification is good enough, which the customer must need to
clarify our validity in our SOC.
On the other hand, we would need to improve their EZ54 performance,
would someone be kind enough to tell me how to get the document of
EZ5XX_PERFORMANCE.PS. Since I cannot find it in the following directory
- BABAGI::LCA:[SPECS.SOLID_STATE.EZXX]
Thank you very much in advance...
Best Regards,
Rocky Lam
HK Technical Support
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 6756.1 | moved.. | SUBSYS::VIDIOT::PATENAUDE | Ask your boss for ARRAY's... | Fri Jun 06 1997 07:43 | 13 |
Rocky, BABAGI files moved to SUBSYS a long while back. It has been mentioned in here quite a few times and there is a note about it in here.. To answer your question though.. To get max throughput on an EZ5x product you MUST use SMALL I/O's. The unit has a low bandwidth but no seek time so you need to capitalize on THAT by the small I/O's. Roger. | |||||
| 6756.2 | notes collision | SUBSYS::BROWN | SCSI and DSSI advice given cheerfully | Fri Jun 06 1997 07:52 | 24 |
The documentation moved from BABAGI:: to SUBSYS::.
I would like to know more about what sort of performance your
customer would like to see. It sounds like the customer asked
about megabytes per second, not I/Os per second. As far as I know,
the drive is capable of 800 I/Os per second. If each I/O command
reads one block, that's a data rate of only 400KB/sec.
A disk drive's performance is typically measured two ways:
commands per second, and megabytes per second. There is a trade-off
between them. If you use larger transfer sizes (16KB per command,
64KB per command, and so on), you can transfer more data per second.
If you use smaller transfer sizes, you can issue more commands per second.
You can't maximize both at the same time.
The hard part is matching the customer's requirements to the devices
available. If the customer needs sub-millisecond access time to widely
scattered data, use an EZ (solid-state) disk. If he needs the
most megabytes per second, get a Winchester disk, and settle for
about 300 commands per second on localized data, and maybe
100 commands per second on widely scattered data. It may be
difficult to predict which disks and configurations will yield
the best performance. What does the customer use the system for?
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