Mysql verileriniz sda da değil sdb de dir. sanırım sistemi yeniden başlattınız umount olmuş. /dev/sdb mount ederek veritabanlarını alabilirsiniz.
güncel veritabanları bunlardır.
my.conf db dizin yolu ve tüm bilgiler:

[root@server3 ~]# cd /
[root@server3 /]# pwd
/
[root@server3 /]# ls -al /mysql2/
total 32
drwxr-xr-x 4 mysql mysql 4096 May 14 01:02 .
drwxr-xr-x 25 root root 4096 May 14 02:04 ..
drwx------ 2 mysql mysql 16384 May 13 19:02 lost+found
drwxr-xr-x 53 mysql mysql 4096 May 14 00:26 mysql
[root@server3 /]# ls -al /mysql2/mysql
total 545564
drwxr-xr-x 53 mysql mysql 4096 May 14 00:26 .
drwxr-xr-x 4 mysql mysql 4096 May 14 01:02 ..
drwx------ 2 mysql mysql 4096 Apr 29 12:56 altunprofil
drwx------ 2 mysql mysql 4096 Apr 29 13:04 anayemektarifi
drwx------ 2 mysql mysql 4096 Apr 29 12:19 apsc
drwx------ 2 mysql mysql 12288 Apr 29 13:02 cemiyet
drwx------ 2 mysql mysql 4096 Apr 29 12:57 denklemdanis
drwx------ 2 mysql mysql 4096 Apr 29 12:56 dernek
drwx------ 2 mysql mysql 4096 Apr 29 13:05 dortyoladsm
drwx------ 2 mysql mysql 12288 Apr 29 13:00 efendita_db1
drwx------ 2 mysql mysql 4096 Apr 29 12:56 efendita_duhanbaca
drwx------ 2 mysql mysql 4096 May 3 11:40 efenditasarim@002dyeni
drwx------ 2 mysql mysql 4096 Apr 29 13:00 enes
drwx------ 2 mysql mysql 4096 May 12 00:32 fitness_efendi
drwx------ 2 mysql mysql 4096 Apr 29 12:21 horde
drwx------ 2 mysql mysql 4096 Apr 29 13:05 hostingler
-rw-rw---- 1 mysql mysql 547356672 May 13 18:42 ibdata1
-rw-rw---- 1 mysql mysql 5242880 May 13 19:05 ib_logfile0
-rw-rw---- 1 mysql mysql 5242880 May 13 02:51 ib_logfile1
drwx------ 2 mysql mysql 4096 Apr 29 13:01 ilanv1
drwx------ 2 mysql mysql 4096 Apr 29 13:06 iostest
drwx------ 2 mysql mysql 4096 May 5 14:18 kadingiyim
drwx------ 2 mysql mysql 4096 Apr 29 13:05 kaliteyonetim
drwx------ 2 mysql mysql 4096 Apr 29 13:01 katredemo
drwx------ 2 mysql mysql 4096 Apr 29 12:58 katre_dincer
drwx------ 2 mysql mysql 4096 Apr 29 13:01 katrewebtasarim
drwx------ 2 mysql mysql 4096 Apr 29 13:01 kiralama_ilan
drwx------ 2 mysql mysql 4096 Apr 29 13:02 kursundekorasyon
drwx------ 2 mysql mysql 4096 Apr 29 13:22 mehmetmutlu_001
drwx------ 2 mysql mysql 4096 Apr 29 13:23 mehmetmutlu_002
drwx------ 2 mysql mysql 4096 May 12 15:37 mehmetmutlu_003
drwx------ 2 mysql mysql 4096 Apr 29 13:25 mehmetmutlu_004
drwx------ 2 mysql mysql 4096 May 10 15:28 mehmetmutlu_005
drwx------ 2 mysql mysql 4096 Apr 29 13:27 mehmetmutlu_006
drwx------ 2 mysql mysql 4096 Apr 29 13:27 mehmetmutlu_007
drwx------ 2 mysql mysql 12288 May 12 02:00 musalpvp
drwx------ 2 mysql mysql 4096 Apr 29 12:13 mysql
drwx------ 2 mysql mysql 4096 Apr 29 13:06 pauforum_frm
drwx------ 2 mysql mysql 4096 Apr 29 12:13 performance_schema
drwx------ 2 mysql mysql 4096 Apr 29 12:20 phpmyadmin_7QtmJd4uqElm
drwx------ 2 mysql mysql 12288 Apr 29 12:19 psa
drwx------ 2 mysql mysql 4096 Apr 29 13:05 rantacar
drwx------ 2 mysql mysql 4096 Apr 29 12:16 roundcubemail
drwx------ 2 mysql mysql 4096 Apr 29 12:17 sitebuilder5
drwx------ 2 mysql mysql 4096 Apr 29 13:08 snlders
drwx------ 2 mysql mysql 4096 Apr 29 13:02 teksaforg_db
drwx------ 2 mysql mysql 4096 Apr 29 13:08 twittersnl
drwx------ 2 mysql mysql 4096 Apr 29 13:01 unalapart
drwx------ 2 mysql mysql 4096 May 1 17:34 unalapart_unal
drwx------ 2 mysql mysql 4096 Apr 29 13:03 uplat
drwx------ 2 mysql mysql 4096 Apr 29 13:04 vps724_ovn
drwx------ 2 mysql mysql 4096 Apr 29 13:08 vps724_sonnet
drwx------ 2 mysql mysql 4096 Apr 29 13:09 vps724_sonorg
drwx------ 2 mysql mysql 4096 Apr 29 13:20 vps724_thaber
drwx------ 2 mysql mysql 4096 Apr 29 12:57 webitibr_bilirkisidb
drwx------ 2 mysql mysql 4096 Apr 29 13:00 zmobilya
[root@server3 /]# du -sh /mysql2/mysql
592M /mysql2/mysql
[root@server3 /]# cat /etc/my.conf|grep mysql2
datadir=/mysql2/mysql


Mount olarak bıraktım yedeklerinizi alırsınız.
Umarım birde özür dilersiniz