Re: [gpfsug-discuss] Spectrum Scale 5 and Reading Compressed Data

Wed, 20 Jan 2021 03:59:55 -0800

I think you need to think about which node the file is being decompressed on (and if that node has plenty of space in the page pool.)
iirc mmchattr works on one of the 'manager' nodes not necessarily the node you typed the command on?
Daniel
 
_________________________________________________________
Daniel Kidger Ph.D.
IBM Technical Sales Specialist
Spectrum Scale, Spectrum Discover  and IBM Cloud Object Storage

+44-(0)7818 522 266 
[email protected]
 
 
 
----- Original message -----
From: Alec <[email protected]>
Sent by: [email protected]
To: [email protected]
Cc:
Subject: [EXTERNAL] [gpfsug-discuss] Spectrum Scale 5 and Reading Compressed Data
Date: Wed, Jan 20, 2021 11:10
 
We have AIX and Spectrum Scale 5.1 and are compressing older data.
 
We can compress data at about 10GB/minute and decompress data wicked fast using mmchattr, when a user reads data from a compressed file via application open / read calls.... it moves at about 5MB/s.  Normally our I/O pipeline allows for 2400MB/s on a single file read.
 
What can we look at to speed up the read of the compressed data, are there any tunables that might affect this?
 
As it is now if the backup daemon is backing up a compressed file, it can get stuck for hours, I will go and mmchattr to decompress the file, within a minute the file is decompressed, and backed up, then I simply recompress the file once backup has moved on.
 
Any advice on how to improve the compressed reads under AIX would be very helpful.
 
Alec
 
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