Hi all,
Can somebody explain this huge difference between 2 (almost) identical
servers:
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dd if=/dev/zero of=test.bin bs=512 count=1024 oflag=sync
524288 bytes (524 kB) copied, 0.00133898 s, 392 MB/s
vs
524288 bytes (524 kB, 512 KiB) copied, 0.3026 s, 1.7 MB/s
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With "hdparm -tT /dev/sda" discrepancies are much smaller but still
noticeable:
Timing cached reads: 15976 MB in 2.00 seconds = 7996.66 MB/sec
Timing buffered disk reads: 2134 MB in 3.00 seconds = 710.98 MB/sec
vs
Timing cached reads: 14282 MB in 1.99 seconds = 7161.56 MB/sec
Timing buffered disk reads: 1172 MB in 3.00 seconds = 390.61 MB/sec
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I would thought all meaningful aspects are identical:
- server model (IBM/Lenovo X3650 M3)
- identical disks (count, brand, model, capacity) and RAID controller
cards (LSI ServeRAID M5014 SAS/SATA Controller)
- RAID settings:
Adapter 0 -- Virtual Drive Information:
Virtual Drive: 0 (Target Id: 0)
Name :
RAID Level : Primary-5, Secondary-0, RAID Level Qualifier-3
Size : 3.629 TB
Sector Size : 512
Parity Size : 929.458 GB
State : Optimal
Strip Size : 128 KB
Number Of Drives per span:5
Span Depth : 2
Default Cache Policy: WriteBack, ReadAdaptive, Direct, No Write Cache
if Bad BBU
Current Cache Policy: WriteBack, ReadAdaptive, Direct, No Write Cache
if Bad BBU
Default Access Policy: Read/Write
Current Access Policy: Read/Write
Disk Cache Policy : Disabled
Encryption Type : None
Is VD Cached: No
- both have BBUs in optimal states
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There is a slight difference in RAID firmware:
FW Package Build: 12.12.0-0085
vs
FW Package Build: 12.15.0-0248
With the newer giving lower results.
Shall I start digging with Lenovo / LSI or am I missing something?
Thanks,
Adam