The default MVFS scaling factor is automatically set, up to a
maximum value of 24, based on available physical memory installed on the host.
If you want to adjust the value of the MVFS scaling factor manually, you can.
When considering setting the scaling factor higher than 24, be aware that
a larger cache might not improve performance on all hosts. The cost of managing
that cache (particularly the locking cost on multiprocessor hosts) can exceed
the benefits.
Table 1 shows
how the MVFS scaling factor should be adjusted based on memory size.
Table 1. Effect of memory size
on the MVFS scaling factor| Memory size (MB) |
Memory<24 |
24<= Memory <512 |
512<= Memory <3072 |
Memory >= 3072 |
|---|
| MVFS Scaling Factor |
0 |
1 |
2 |
size/1024 |
In Table 1,
the value of size excludes memory required by the operating
system kernel. For size values greater than 3072 MB (3
GB), the MVFS scaling factor is rounded down to the nearest multiple of 1024
MB. For example, if a host has 4096 MB (4 GB) of physical memory and the kernel
consumes 100 MB, the MVFS scaling factor is set to 3.
You can use setcache
–mvfs –persistent –scalefactor to override the default scaling
factor setting. On Windows®, you can also use the ClearCase® program
in Control Panel. On the MVFS Performance page, set
the scaling factor value in the Scaling factor to initialize MVFS
with more memory for better performance field. Click OK.
Increasing
the scaling factor by one requires about 500 KB of additional kernel memory
(200 KB nonpageable, 300 KB pageable).
Note: If you use setcache to
request more kernel memory than is currently available, the request fails
with a not enough space error. If this happens, you must
request a smaller cache size or else terminate unnecessary processes that
are consuming kernel memory.
Changing the value of the scaling
factor scales all of the MVFS cache sizes proportionally as shown in
Table 2.
Table 2. Effect of MVFS scaling factor on
individual MVFS cache sizes| MVFS cache name |
scaling factor = 0 |
scaling factor = 1 |
scaling factor = 2 |
scaling factor = f (f > 2) |
|---|
| mnode Cache (mnmax) |
4096 |
8192 |
12,288 |
4096(f+1), f<4; 2048(f+7), f>4 |
| mnode Freelist Max |
901 |
1802 |
2703 |
0.22 mnmax |
| Cleartext Freelist Max (Linux® and the UNIX® system) |
900 |
1800 |
2700 |
900(f+1) |
| Cleartext Freelist Max (Windows) |
900 |
1800 |
1800 |
1800 |
| DNC File Cache |
800 bytes |
1600 bytes |
2400 bytes |
800(f+1) bytes |
| DNC Directory Cache |
200 bytes |
400 bytes |
600 bytes |
200(f+1) bytes |
| DNC ENOENT Cache |
800 |
1600 |
2400 |
800(f+1) |
| RPC Handle Cache |
5 |
10 |
15 |
5(f+1), f < 2
10(f+1), f > 2 |
| readdir Block Cache |
2 |
4 |
6 |
2(f+1), f < 26, f > 2 |