memory on a scsi card?

[nalletill1000]

I have tried to find information about exatcly what a memory does on a scsi controller card, and so far nothing. Anyone here that has the knowledge and take the time to explain it for me?
Thanks in advance

[Lazn_Work]

It is usually found on a RAID card.

It will have several modes that it can use this memory in: http://www.data-storage.co.uk/raid/raid_explained.htm
"Write Through:
With Write Through Cache the data is written to both the cache and drive once the data is retrieved. As the data is written to both places, should the information be required it can be retrieved from the cache for faster access. The downside of this method is that the time to carry out a Write operation is greater the time to do a Write to a non cache device. The total Write time is the time to write to the cache plus the time to Write the disk.

Write Back:
With Write Back Cache the write operation does not suffer from the Write time delay. The block of data is initially written to the cache, only when the cache is full or required is the data written to the disk.

The limitation of this method is that the storage device for a period of time does not contain the new or updated block of data. If the data in the cache is lost due to power failure the data cannot be recovered. When using Write Back Cache a battery backup module would prevent data loss in a RAID power failure."

Personally my feeling is that if the card doesn not have a battery backup, do not set your cache to Write Back mode.

==>Lazn

[nalletill1000]

thanks.. you found what i did not... and i got my question answered..