Is it worth it to upgrade the memory on a Raid Controller?

D

Draugauth

Limp Gawd
Joined
Mar 29, 2007
Messages
302
My raid controller has 1GB of SDRAM on it and can support up to 2GB. Will that be good for improving the speed of the raid? Is it worth the 60-80$ for good ECC Buffered memory?
 
I am confused why the upgrade is so expensive. Can your raid controller use standard ram or does it not recognize that?
 
If you are just a single user, writes will "seem" to finish faster while it dumps into the cache. Where it is more beneficial is when having many users reading from the drives, where the controller will have the ability to cache often-used records.
 
If you have a quite old operating system, it can improve performance.
A modern OS is using any unused RAM for read-caching. These are several GB RAM
that is much much faster than the controller RAM. In such a case, regular RAM is important,
not controller RAM.

Some OS's like Solaris with ZFS even caches writes in regular RAM (if not sync-writes)
to transform small random writes to large sequential writes.

On a modern OS more controller RAM is quite useless
 
_Gea said:
If you have a quite old operating system, it can improve performance.
A modern OS is using any unused RAM for read-caching. These are several GB RAM
that is much much faster than the controller RAM. In such a case, regular RAM is important,
not controller RAM.

Some OS's like Solaris with ZFS even caches writes in regular RAM (if not sync-writes)
to transform small random writes to large sequential writes.

On a modern OS more controller RAM is quite useless
Click to expand...

this is about memory cache on HW raid not on OS side, and not related with OS memory.

if we are talking about software Raid on current OS, more memory would be utilized :)
 
cantalup said:
this is about memory cache on HW raid not on OS side, and not related with OS memory.

if we are talking about software Raid on current OS, more memory would be utilized :)
Click to expand...

OS read or write caching is independent from Software or Hardware Raid or Raid at all.
 
_Gea said:
OS read or write caching is independent from Software or Hardware Raid or Raid at all.
Click to expand...

once the OS calls (API) to the RAID,, this will be a different story...

OS would do cache, but for a limited time...

imagine where CPU have L1 cache and L2 Cache :D

this is talking about Hardware RAID memory cache, this is out of scope on OS memory as I understand:D
 
On a modern OS more controller RAM is quite useless
Click to expand...

It is very useful for the write back cache on parity raid although for a single user I am not sure how much increased cache will help.
 
Ok thanks for the info. I'll put it on my list of upgrades but at a lower priority since I currently have a 1gb memory stick on the controller.
 
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