January 22, 201511 yr Hello, im operating a LTO6 tapedrive in a LSI 9207-8i HBA and using LTFS on a Win7 system. I have the problem that the tapedrive isnt reading or writing fast enough although i read or write the date from a local hd with ~160 MB/s read/write. The tapedrive should be able to write/read with 54–160 MB/s (Specifications) but i sometimes reach only 45-50 MB/s and have the shoeshining-effect. Could the firmware / BIOS of the HBA a reason for this problem? Here are my current versions: Controller Number : 0 Controller : SAS2308_2(D1) PCI Address : 00:02:00:00 SAS Address : 500605b-0-08af-6420 NVDATA Version (Default) : 11.00.00.05 NVDATA Version (Persistent) : 11.00.00.05 Firmware Product ID : 0x2214 (IT) Firmware Version : 17.00.01.00 NVDATA Vendor : LSI NVDATA Product ID : SAS9207-8i BIOS Version : 07.33.00.00 UEFI BSD Version : 07.24.01.00 FCODE Version : N/A Thanks in advance!
January 22, 201511 yr The HBA is not the problem, as you mention the problem is" sometimes". You can update, but I don't expect a change. LTFS (like all tape operations) requires steady stream of data to avoid the shoeshining. Hence QFS is often used to cache data headed to the tape drive. With LTFS, file size will be a big factor as for each file there will be a time gap. More small files means lower streaming rate.
January 23, 201511 yr Author Thanks c3 for your reply! I only backup or restore large files with about 5-30 GB each and dont use compression. Sometime means that i only have get one times a high rate when i restored data from tape back to HD, i think it was about 80-90 MB/s. At the rest of about 15 times when i used the tape drive for backup (most) or restoring (few) data with LTFS, i had about only 45-50 MB/s. My tapedrive is from "tandberg". When i tested the perfomance with the testing-tool from tandberg, i get ~120 MB/s. I was also able to store only ~1,05 TB on a 1,31 TB LTO5 tape. I think this is a normal effect of shoeshining. Yesterday i setup my OS new, because the installation was some years old. I installed again Win7 SP1 and LTFS. Since yesterday i get 80 MB/s on some quick tests! The tandberg testing-tool still reach ~120MB/s. I will do some more test in the next days to confirm the gain. Im already happy with this rate and hope i will be able to store more data on a tape as before. However, do you have some ideas to improve the performance even more? 120 MB/s should be able, but i dont would need more than 100 MB/s (Gbit-LAN).
January 23, 201511 yr I was also able to store only ~1,05 TB on a 1,31 TB LTO5 tape. I think this is a normal effect of shoeshining. This is actually the effect of the anti-shoeshine technology which allows the tape to continue forward without writing data. When shoeshining, the drive actually stops and reverses direction, reclaiming this space, then writing again as the tape begins forward again. But as you mentioned, the back and forth motion adds wear to the media. This is compounded by the LTFS use of bands to improve file access.
January 28, 201511 yr Author Thanks c3! I thought this is a effect of shoeshining, because this wiki-entry: "Shoe-shining decreases the attainable data transfer rate, drive and tape life, and tape capacity." I have done some tests the last days.. I got ~80 MB/s for backup and 70 MB/s for restore data. The files were >20 GB. But then, when i tried to backup a dataset (whole set 1,15 TB, files ~7-8GB) which i already unsuccessfully tried often before to backup to a LTO5 tape (1,31 TB), i get again about ~40 MB/s and the data doesnt fit again on the tape. As next, i combined a part (587 GB) of this dataset to 5 archives (7z) to get larger files. When i backuped these archives i get 70 MB/s, but these 587 GB takes 772 GB on the tape. I checked some other tapes which i have already recorded in the past. There i have 1200-1300 GB data on LTO5 tapes, with different file sizes (2-25 GB). Any idea whats going wrong?
January 28, 201511 yr unfortunately, tapes do not have a fixed capacity. Even uncompressed the amount of data that will fit on a tape is slightly variable. With compression, it varies widely. It's possible the tape just has some unusable areas. Do you have access to the data from the tape CM?
January 28, 201511 yr Author It's possible the tape just has some unusable areas. So the qualitiy of the tapes (i tried two) could be the reason of the high capacity usage-and the low backup-rate of 40 MB/s? Sorry, what is tape CM?
January 30, 201511 yr Author With the standard LTFS-tools i can only read the data for loads, data writen and data readed. I will try to find a way to read the whole CM.
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