--set the number of days in @daystillexpiry parameter(like 1 month = 30 days) after expiry status, set to 0/1 (0=all archives, 1=only archives with “delete expired items” on) in @expiryarchivesonly parameter.
And run below query against vault store database.
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declare @daystillexpiry smallint
set @daystillexpiry = '600'
declare @expiryarchivesonly bit
set @expiryarchivesonly = '0'
SELECT a.ArchiveName, s.ArchivePointIdentity, RCE.RetentionCategoryName,sum(ItemSize)as TotalKB, count (*) as 'Num Items Eligible' FROM Saveset S
inner join ArchivePoint
On S.ArchivePointIdentity = ArchivePoint.ArchivePointIdentity
INNER JOIN EnterpriseVaultDirectory.dbo.Root r on r.VaultEntryID = ArchivePointID
INNER JOIN EnterpriseVaultDirectory.dbo.Archive a on a.RootIdentity = r.RootIdentity
join EnterpriseVaultDirectory.dbo.RetentionCategoryEntry RCE on S.RetentionCategoryIdentity = RCE.RetentionCategoryIdentity
where RCE.retentionperiod < '99999' and datediff(dd,getdate(),(dbo.fnExpirationDate(-(rce.retentionperiod),(rce.retentionperiodunits),(s.iddatetime))))< @daystillexpiry and a.deleteexpireditems >= @expiryarchivesonly
GROUP BY ArchiveName, ArchivePointID, RCE.RetentionCategoryName, s.ArchivePointIdentity
Order by archivename Asc