SAP HANA is a relational in-memory database from SAP, in which data is stored and processed exclusively in RAM. Disks are used only for logging and storing backups required for system recovery. You can find a lot of information on the advantages of such a solution on the Internet. But today we want to talk about the cons.
We got acquainted with SAP HANA in 2014. Since then, we have been faced with many features of the in-memory database, which have left various imprints in our history. The experience of operating this database introduced us to several of its disadvantages:
Long startup time of the system.
Severe limits on the amount of consumed RAM.
Fight against fraudulent inquiries and users.
Today we will talk about the first problem - the long startup time of the system. This is one of the key issues in technology. The RAM is fast, the calculations are done on the fly, but when the system is rebooted, the data into this very memory must be loaded from the disks. Until this happens, you will not be able to log into the system, or it will work VERY slowly. Over time, the problem gets worse: the larger the base, the longer the system will start.
Initial data
: 12 TB RAM, 448 , SSD-. , 10 000 . , . , 15 .
80 . , . , .
0: Intel Optane
2017 Intel Optane. , . in-memory .
SAP HANA 2.0 SPS 03. Intel Optane 2019 , . : Intel Optane. , . , .
:
|
|
|
Optane |
CPU(s) |
240 |
224 |
Model |
62 |
85 |
Model name |
Intel® Xeon® CPU E7-8880 v2 @ 2.50GHz |
Intel® Xeon® Platinum 8280M CPU @ 2.70GHz |
L1d cache |
32K |
32K |
L1i cache |
32K |
32K |
L2 cache |
256K |
1024K |
L3 cache |
38 400K |
39 424K |
Memory |
128 GB x 48 |
32 GB RDIMM x 24 |
Optane Memory |
- |
128 GB x 24 |
|
|
|
|
|
58 |
9 50 |
Intel Optane 6 . . — . , Intel Optane — .
, . , Optane - . , . , , SAP.
1: Fast Restart —
SAP HANA 2.0 SPS 04 — Fast Restart Option. . , .
tmpfs — , , . NUMA- tmpfs, . , . , .
cat /sys/devices/system/node/node*/meminfo | grep MemTotal | awk 'BEGIN {printf "%10s | %20s\n", "NUMA NODE", "MEMORY GB"; while (i++ < 33) printf "-"; printf "\n"} {printf "%10d | %20.3f\n", $2, $4/1048576}'
:
, 0. basepath_persistent_memory_volumes «;».
: 1,5 TB RAM 12 TB RAM. , .
:
Column Store (CS). HANA, . .
. : , , . .
|
|
1,5 TB RAM |
12 TB RAM |
||
|
|
Fast Restart |
C Fast Restart |
Fast Restart |
C Fast Restart |
CS |
3 |
23 |
65 |
2,6 |
|
15 |
12,5 |
76 |
15 |
:
1,5 TB CS 8 . , .
12 TB CS 25 , 5 .
, Fast Restart : , .
2:
. , . .
: , , , . , . , .
SAP HANA : delta_datashipping, logreplay, logreplay_readaccess. , logreplay logreplay_readaccess .
delta_datashipping. HANA . 15 . . , . , .
logreplay. HANA 1.0 SPS 10 HANA 2.0. . , , , .
logreplay : global.ini → [system_replication] → operation_mode = logreplay. .
. , .
12 TB :
|
|
delta_datashipping |
72 |
logreplay |
2 1 |
: 40 . , , .
. 80 , 15 .
, . SAP «» HANA, , . , .
HANA DB? .