But i found some site stated otherwise
http://servervirtualization.blogs.techtarget.com/2008/01/14/searchservervirtualizationcom-products-of-the-year-not-without-their-share-of-snubs/
that's why Citrix must partner with storage vendors – for instance, Symantec's Veritas NetBackup 6.5 supports Citrix SenServer backup.
http://searchstorage.techtarget.com/news/article/0,289142,sid5_gci1307658,00.html