| 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 |
I have a new customer that wants to have the system disk in the shared bus...I understand this is not valid ... any explanation on it [Posted by WWW Notes gateway]
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 6459.1 | more information required | TROOA::MSCHNEIDER | [email protected] | Mon Mar 10 1997 21:19 | 7 |
I think we'll need a bit more data if you expect a response. For
example:
What systems?
What shared bus?
Operating system?
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| 6459.2 | cache and swap | MSDOA::mko-ras-port-2.mko.dec.com::KLOPEZ | Ay, Caramba! | Tue Mar 11 1997 11:31 | 21 |
AlphaServer 4100, HSZ40, Digital UNIX, 512 MB, 12 GB Oracle DB, DECsafe. I understand this is not possible, and why. Unfortunately I have already sold it. We have talked to the customer and we are trying to convince him to use the local bus and LSM to mirror his disks. The bad news is that he claims he wanted to use cache for this swap device and this might affect performance. I have looked for information confirming if this is true or not, but I haven't found it. Do we really benefit from having controller cache for a swapping? I think that by placing the operating system disks on an independent bus on the KZPDA we would have dedicated 20 MB/s and whatever I/O/s vs having to share the HSZ40 eventhough we don't have cache. What do you think? Katya | |||||
| 6459.3 | cache is not the only consideration | TROOA::MSCHNEIDER | [email protected] | Tue Mar 11 1997 22:29 | 15 |
Absolutely better to have the system/swap disk on the KZPDA rather than
behind the HSZ40. Should be reduced latency without the RAID
controller and no other disks to share the pipe with ... also you get a
fast-wide pipe to the disk, whereas behind the HSZ40 it is a
fast-narrow pipe. Remember the HSZxx controllers are a solution to
provide hardware RAID and connect large numbers of disks to a single
SCSI adapter .... it is not necessarily the fastest performance
solution. Talk to the folks at the Benchmark centers. Often when
doing benchmarks where smaller numbers of disks are involved
the best performance solution is lots of KZPSA controllers with the
disks directly attached to the SCSI bus without an intervening HSZxx
controller.
If they really insist on cache then sell them a KZPAC or KZPSC internal
RAID controller to connect their system disks.
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| 6459.4 | Thanks!!!! | MSDOA::mko-ras-port-12.mko.dec.com::KLOPEZ | Ay, Caramba! | Wed Mar 12 1997 08:19 | 6 |
This is the kind of information I was looking for, I appreciate your help, Katya | |||||